Lee Coulthard Fluvial Geomorphology and Large Dams -­‐Geomorphology is “the study of the physical features of the surface of the earth and their relation to its geological structures.” (Oxford). Fluvial geomorphology concerned with the study of water-­‐channels. -­‐Large dams play a role in fluvial geomorphology because they impact the water-­‐channels they are built upon through water discharge and sediment flux regulation. There is scientific consensus that large dams impact flux and discharge in some way, however there is uncertainty as to how much quantitatively (Vorosmarty, Meybeck, Fekete, Sharma, Green, and Syvitski, 2003). -­‐The negative impacts pressed upon natural ecosystems downstream from each dam is not well-­‐
studied. Historical focus regarding dams has been around economics and politics, with concern becoming broadened to human populations in recent years and now ecology as well. Fluvial Geomorphology and the World Commission on Dams -­‐Though the WCD does make several mentions of large dams and their relation to sediment flux, Petts and Gurnell (2005) note that they do not ever directly reference the word 'geomorphology' once. -­‐As well, Klaus Dingwerth (2005) levies some criticisms at the democratic legitimacy of the WCD, such as that they lacked early popularity, making them difficult to access for some stakeholders, and that their internal definition of a stakeholder was define by a small, inclusive group. Large Dams and Water Discharge -­‐Large dams decrease ecosystem functions and lower biodiversity by altering natural surface and sub-­‐surface water levels of hydrological channels (Zhao, Liu, Deng, Dong, Cong, Wang, Yang, & Yang, 2011). They alter natural flow patterns and flood regimes by lowering overall water discharge (Gupta, Kao, & Dai, 2012). Water discharge is the volume rate of water flow, and the sediment flux rate is dependent upon the rate of water discharge (Gupta, et. al., 2012). -­‐The area immediately downstream from the dam is most heavily impacted. As more tributaries contribute back into the water-­‐channel downstream, the effects of the dam are lessened. (Zhao et. al., 2011) -­‐The reservoirs of large dams allow for massive amounts of evaporation, removing large quantities of water and also increasing the salinity to levels that can be dangerous to ecosystems and even machinery (McCully, 2001). Large dams and Sediment Flux -­‐Large dams drastically reduce the natural flux in sediment from the land to the ocean (Gupta et. al., 2012). Erosion occurs downstream to compensate for sediment trapped in the reservoirs (Dai et. al., 2008). -­‐Sediment carries nutrients through the water and deposits them wherever it settles. When sediment is being held back in dam reservoirs, low-­‐lying plains will not receive necessary nutrients and this can impact natural ecosystems, including fish stocks (UNDP, 2007). -­‐Critics say that humans are not actually altering sediment flux through dam construction and that it is caused naturally by the climate, or that the sediment flux is actually increasing. This is not true as an increase in sediment flux can be attributed to other factors, such as deforestation occurring after dam construction. As well, climate change has been noted by Dai, Yang, and Cai (2008) to not have a noticeable effect on sediment flux. -­‐Decommissioning large dams eventually restores downstream ecosystems, however the flush of sediment can have negative effects, especially if the sediment is retaining toxins from upstream mining or industry (WCD, 2000). Sediment flushing to clear reservoir space can have similar effects. -­‐Reduced ability to regulate floods, lowered hydroelectric productivity, and coastal ecosystem die-­‐off are just some of the effects that reduced natural sediment flux can have as a result of a large dam (Vorosmarty et. al., 2003) Bibliography Dai, S.B., Yang, S.L., & Cai, A.M. (2008). Impacts of dams on the sediment flux of the Pearl River, southern China. CATENA, 76(1), 36-­‐43. doi: 10.1016/j.catena.2008.08.004 Dingwerth, K. (2005). The democratic legitimacy of public-­‐private rule making: What can we learn from the World Commission on Dams? Global Governance, 11 (1), 65-­‐83 Gupta, H., Kao, S-­‐J., & Dai, M. (2012). The role of mega dams in reducing sediment fluxes: A case study of large Asian rivers. Journal of Hydrology, 464-­‐465, 447-­‐458. doi: 10.1016/j.hydrol.2012.07.038 Walling, D.E. (2006). Human impact on land-­‐ocean sediment transfer by the world's rivers. Geomorphology, 79 (3), 192-­‐216. doi: 10.1016/j.geomorph.2006.06.019 Maeck, A. Delsontro, T., McGinnis, D.F., Fischer, H., Flury, S., Schmidt, M., Fietzek, P., & Lorke, A. (2013). Sediment trapping by dams creates methane emission hot spots. Environmental Science & Technology, 47 (15), 8130-­‐8137. doi: 10.1021/es4003907 McCully, P. (2001). Silenced Rivers: The Ecology and Politics of Large Dams. London, GBR: Zed Books. Papanicolaou, A., Barkdoll, B.D. (2011). Sediment dynamics upon dam removal. Reston, VA: American Society of Civil Engineers. Petts, G. E., & Gurnell, A. M., (2005). Dams and geomorphology: Research progress and future directions. Geomorphology, 71 (1), 27-­‐47. doi: 10.1016/j.geomorph.2004.02.015 Syvitski, J.P.M., Vorosmarty, C.J., Kettner, A.J., & Green, P. (2005). Impacts of humans on the flux of terrestrial sediment to the global coastal ocean. Science, 308 (5720), 376-­‐380. doi: 10.1126/science.1109454 UNDP. (2007). Beyond scarcity: Power, poverty, and the global water crisis. United Nations Development Programme. Vorosmarty, C.J., Meybeck, M., Fekete, B., Sharma, K., Green, P., & Syvitski, J.P.M. (2003). Anthropogenic sediment retention: major global impact from registered river impoundments. Global and Planetary Change, 39 (1), 169-­‐190. doi: 10.1016/S0921-­‐
8181(03)00023-­‐7 World Commission on Dams. (2000). Dams and Development: A New Framework for Decision-­‐
Making. London, UK: Earthscan Publications Ltd. Zhao, Q., Liu, S., Deng, L., Dong, S., Cong, Wang, Yang, Z., & Yang, J. (2011). Landscape change and hydrologic alteration associated with dam construction. International Journal of Applied Earth Observation and Geoinformation, 16 (1), 17-­‐26. doi: 10.1016/j.jag.2011.11.009 Big Dams: Environmental Impacts •
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Jackie Mok Chemical composition of water changes when flowing water is stilled o
Altered nutrient levels (increase in plankton and algae) o
Different levels of oxygen and nitrogen – turbidity of water o
Increased dissolved metals – increased acidity of oxygen depleted water at depth more capable of dissolving metals such as iron, manganese, and methylated mercury o
Increased salinity from stagnation and also agricultural irrigation Atmospheric changes o
Methane GHG release methogenesis from anoxic organic matter decomposition o
Large releases from organic matter in flood zone of young reservoirs o
Negligible on the grand scheme of climate change o
Large reservoir increases evaporation and radiative absorption which can change the microclimate in the area Biosphere o
Dams create a large barrier for migration of species o
Separates breeding habitat with rearing habitat o
Fish ladders to address this – however the focus is on upstream migration neglecting downstream movement o
Large reservoir encroaches on territory of terrestrial animals (preference for valley bottoms) o
Changed composition of river system – temperature, oxygen and nitrogen levels o
Native species ill adapted, Invasive species often thrive o
Release of water from surface [epilimnetic (warmer all year around)] or depth (hypolimnetic (cooler in summer warmer in winter)] of reservoir effects temperature of water downstream o
Flow of the river is controlled by anthropogenic demands for water and power which can vary greatly from natural flow patterns o
Timing/Magnitude o
Eg. Glen Canyon Dam on the Colorado River September peak from 2000m3 to 700m3 o
Effect on species (eg. Breeding ground selection) o
Change flood plain, duration, timing, and frequency Individual variability in Dams References Asmai, K. et al. (2000) Dams and development a new framework for decision-­‐making. World Commission on Dams. Kasper, D., Forsberg B., João H. Amaral K., Leitão R., Py-­‐Daniel S., Wanderley R. Bastos, Malm O. (2014) "Reservoir Stratification Affects Methylmercury Levels in River Water, Plankton, and Fish Downstream from Balbina Hydroelectric Dam, Amazonas, Brazil." Environmental Science & Technology 48.2 (1032-­‐040). McCully, P. (1996) Silenced Rivers: The Ecology and Politics of Large Dams. London: Zed. Prowse T., Wrona F., Power G. (2013) Threats to Water Availability in Canada: Dams, Reservoirs and Flow Regulation. Environment Canada Key Water S&T Reports. Natasha Felstead
The Impact of Dams on Fisheries
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Fish populations are highly dependant upon the characteristics of their aquatic habitats, which support all their biological functions. Migratory fish, which require different environments throughout different stages of their life cycle, are particularly affected by the construction of dams because they have to move from one environment to another to survive. The construction of a dam can block or delay fish migration, which can contribute to the decline or even extinction of a species that relies on the horizontal movement between feeding and breading grounds. There are several types of fish passages: Pool fish passes, Denil Fish Passes, Nature-­‐like bypass channels, fish lifts or locks, and transportation programs. Mortality rates from fish migrating downstream can be significant, from fish passing through hydrolic turbines and from fish going over spillways. Current mitigation techniques to prevent fish from entering hydrolic turbines include: Physical screens and angled bar racks or louvers to prevent surface bypass. Downstream migration problems have not been well studied or considered Dams purposely or inadvertently alter the downstream hydrology, including flooding. If damns reduce or eliminate downstream flooding, fisheries productivity can be negatively impacted. River reservoirs change lotic environments into lentic environments. Fish species that spawn in relatively fast moving water can be severely reduced or eliminated Dams purposely or inadvertently alter downstream hydrology, including flooding. When dams reduce or eliminate downstream flooding, fisheries productivity can be impacted significantly. When several dams are constructed on the upstream tributaries of a river ecosystem, the flow of nutrients may be blocked. This will negatively affect the productivity of fisheries located downstream, including marine and estuary environments. Smaller reservoirs are more productive on a per unit area basis than larger reservoirs. Smaller, shallower reservoirs have a greater surface area to volume ratio, which result in higher primary production. Greater primary production typically enhances fishery yields. The introduction of exotic fish species in reservoirs and tailwaters can increase fisheries yields, as long as the species is environmental compatible and culturally accepted. In dam reservoirs, there is usually a faunal shift from river-­‐adapted species to lake-­‐adapted species. Species diversity in reservoirs usually declines over time as river-­‐adapted species fade. Works Cited Food and Agriculture Organization of the United Nations: Opportunities, Challenges and conflict resolution. “Dams, Fish and Fisheries.” 2001. The Environmental Agency of the United Kingdom. Types of Fish Passes. 2014 йил 16-­‐January. 2014 йил 30-­‐January <www.environment-­‐agency.gov.uk/business/sectors/37579.aspx>. Emily Takimoto 52486107 Definitions § Displaced Persons: referring to both ‘physical displacement’ and ‘livelihood’ displacement or deprivation – including: relocation or loss of shelter; lost assets or access to assets; or loss of income sources or means of livelihood (WCD 102). § Resettlement: covers all direct economic and social losses resulting from land taking and restriction of access, together with the consequent compensatory and remedial measures (World Bank 5). o It is important to study the human component of dams because it is rare to find a river whose natural function is not used or appreciated by people in some fashion Social and Economic Impacts § Cornea’s Impoverishment Risks and Reconstruction Model & Chapter 4 of WCD Report § Threatens vulnerable communities – form of livelihood displacement: disrupts local economies, deprives people of their means of production and dislocates them from existing socio cultural setting § Disproportionate affect on Indigenous communities § Downstream effects are largely unaccounted for § Replacement costs – issues of domestic law, measures of valuation, and intangible assets § An integrative approach is possible, and necessary § Issue of equity and distribution Strategic Priorities and Proposed Guidelines by WCD § Reduce and recognize the risk of conflicts § Lower overall costs. § Affected people are recognized as beneficiaries § Affected people are an intrinsic component in negotiations and mitigation plans § Install a stronger decision-­‐making process World Bank Policy Objectives Regarding Involuntary Resettlement § OP 4.12 àInvoluntary Resettlement Policy – established in December 2001 o “…ensures that affected people are assisted in their efforts to improve, or at least restore, their standards of living, in a manner that is consistent with their cultural preferences” (UNEP). o Built on the principle of informed participation of the affected people in resettlement planning and implementation § Projects are not considered complete until agreed plans are fully implemented § Careful analysis of all other feasible alternatives o The Bank has been criticized for their lack of transparency, democracy and participatory development in the decision making process – through this policy framework they are attempting to alleviate particular challenges Inadequacies -­‐ Lack of Legitimacy § Guidelines proposed by WCD are not legally binding § Need a larger focus on resettlement with development and rehabilitation § Move away from a managerialist approach: a focus only on managing a given level of displacement and simplifying the experiences and interests of those displaced Works Cited Bartolome, Leoopoldo Jose, Chris De Wet, Harsh Mander, and Vijay Kumar Nagraj. WCD Thematic Review: Displacement, Resettlement, Rehabilitation, Reparation, and Development. Working paper. N.p.: n.p., 2000. Print. Cernea, Michael. "The Risks and Reconstruction Model for Resettling Displaced Populations." World Development 25.10 (1997): 1569-­‐587. Dams and Development: A New Framework for Decision-­‐making. London: Earthscan, 2000. "Ext Opmanual -­‐ OP 4.10 – Indigenous Peoples." Operational Manual. The World Bank, Dec. 2001. Web. 03 Feb. 2014. "Ext Opmanual -­‐ OP 4.12 -­‐ Involuntary Resettlement." Operational Manual. The World Bank, Dec. 2001. Web. 03 Feb. 2014. Involuntary Resettlement Sourcebook: Planning and Implementation in Development Projects. Washington, DC: World Bank, 2004. McDonlad-­‐Wilmsen, Brooke, and Michael Webber. "Dams and Displacement: Raising the Standards and Broadening the Research Agenda." Water Alternatives 3.2 (2010): 142-­‐61. Scudder, Thayer. "The Human Ecology of Big Projects: River Basin Development and Resettlement." Annual Review of Anthropology 2 (1973): 45-­‐55. "The World Bank Position on the Report of the World Commission on Dams." Dams and Development Project. United Nations Environment Programme, Dec. 2001. Web. 03 Feb. 2014. <http://unep.org/dams/documents/default.asp?documentid=493>. Big Dams and Health Impacts
Courtney Smaha
Benefits of Dams • provides water for irrigation which can be maintained throughout the dry season thus inhibiting famine • provides a reliable source of drinking water, when it would otherwise not be available • aids in electricity production which reduces reliance on fossil fuels and therefore a health benefit due to a decrease in pollution
• also provides flood mitigation which could be another potential hazard to health Inequality of Impact • those who benefit from dams typically reside in urban locations • those living in rural areas, riparian communities, or downstream from the dam are negatively affected by big dams Disease Basics • Communicable transmission and vector transmission • Most deaths in low income countries are due to communicable diseases, these deaths can easily be avoided • These diseases are promoted by population density, and the building of dams • Still water is a preferable breeding ground for insects therefore causing an outbreak of insects that have the potential to carry disease Common Communicable Diseases Associated to Dams • schistosomiasis, malaria, encephalitis, hemorrhagic fevers, gastroenteritis, intestinal parasites, and filarisis
Non Communicable Disease
• Toxic cyanobacteria (algae blooms) caused by eutrophication (nutrient enrichment) of waters Mental Health
• displacement due to dam projects, and troubles associated with relocation Health Impact Assessment
• attempting to solve the problem, before it is a problem • assessing potential for disease through health care experts and community/stakeholder input Challenges
• Temporal and spatial boundaries of disease do not coincide with dam development and duration • Disease outbreak and mental health problems associated with dam’s are incredible hard to predict, and may be underestimated or overestimated • Who is responsible for absorbing the cost of health? Sources • Cairncross, Sandy. "Dams And Disease: Ecological Design And Health Impacts Of Large Dams, Canals And Irrigation Systems." Transactions of the Royal Society of Tropical Medicine and Hygiene 94.4 (2000): 464. Print.
• Bhatia, Rajiv, and Aaron Wernham. "Integrating Human Health Into Environmental Impact Assessment: An Unrealized Opportunity For Environmental Health And Justice." Environmental Health Perspective 14.4 (2009): 991-­‐1000. http://www.ncbi.nlm.nih.gov/pubmed/18709140. Web. 30 Jan. 2014.
• "Human Health and Dams." World Health Organization Sustainable Development and Healthy Environments 1 (2000): 4-­‐36. http://www.who.int/docstore/water_sanitation_health/vector/dams.htm. Web. 30 Jan. 2014.
• Jackson, Sukhan, and Adrian Sleigh. "Resettlement for China's Three Gorges Dam: Socio-­‐
Economic Impact and Institutional Tension." Communist and Post-­‐Communist Studies 33 (2000): 223-­‐241. www.elsevier.com. Web. 30 Jan. 2014.
• Lerer, Leonard B, and Thayer Scudder. "Health Impacts Of Large Dams." Environmental Impact Assessment Review 19.2 (1999): 113-­‐123. Print.
• Orr, Cailin. "Dams And Development: A New Framework For Decision-­‐Making. The Report Of The World Commission On Dams. 2000. Earthscan Publications Ltd., London. 448 Pp. $89.95 Hardcover, $29.95 Paperback. Also Available Online: Www.dams.org.." Environmental Practice 3.03 (2001): 191. http://www.internationalrivers.org/files/attached-­‐
files/world_commission_on_dams_final_report.pdf. Web. 30 Jan. 2014.
• Ross, Allen. "Schistosomiasis." New England Journal of Medicine 347.10 (2002): 766-­‐768. http://go.galegroup.com.. Web. 30 Jan. 2014.
• Tetteh, I. "An Analysis Of The Environmental Health Impact Of The Barekese Dam In Kumasi, Ghana." Journal of Environmental Management 72.3 (2004): 189-­‐194. http://www.sciencedirect.com.ezproxy.library.ubc.ca/science/article/pii/S03014797040009
69. Web. 30 Jan. 2014.
• Yamada, Tadataka. Textbook of gastroenterology. 5th ed. Chichester, West Sussex: Blackwell Pub., 2009. http://books.google.ca/books?id=69Ttbl6ewp8C&pg=PT4955&lpg=PT4955&dq=http://ww
w.who.int/ctd/+schisto/epidemio.htm. Web. 30 Jan. 2014. Introduction Amy Luo 26376111 • Dams and hazard prevention o Seasonal and climate variations impede efficient use of river runoff, the extreme cases being floods and droughts o Store water in times of surplus and release it in times of scarcity o Aggregate storage capacity of ~6000km3, dams make significant impact on the management of water resources and hazard prevention • Dams as a hazard? o American Society of Civil Engineers (ASCE) graded dams in the United States a D in their “1998 Report Card for American Infrastructure” § Reasons including, age, downstream development, dam abandonment, & lack of funding o Dam failure can result in disastrous effects, serious property damage and deaths Dams role in prevention & mitigation of hazards • World Commission on Dams has 2 perspectives o Narrow focus on role of dams in flood control o Broader approach to flood management as an objective • Flood control benefits o Big dams control floods by storing flood waters in a reservoir and release slowly over time o Store portion of flood in order to delay peak § Minimizes chance of coincident peak from floods in different tributaries arriving at same time, reduces probability of breaching dykes o Only one main measure of performance – extent of flood peak reduction o Can be very effective i.e. Japan, large dams have dramatically reduced flash floods from exceptionally steep and short rivers • However… o Many risk factors from dams breaking à amplify flood damage o Dams and reservoir are improperly operated à develop false sense of security o Dams are incredibly expensive and several drawbacks as mentioned earlier o Dams have provided important flood control, but some have actually increased vulnerabilities of riverine communities o Growing concern of cost and effectiveness in addressing floods long-­‐term • Integrated flood management o Difficulty in managing the implications of floods in relation to people and communities, thus need a different approach § Set objectives in terms of predicting, managing and responding to floods, rather than “band-­‐aid” flood control o 1960-­‐1985 US government spent $38 billion on flood control (large dams), but avg damage continued to increase o After 1993 Mississipi flood US Army Corps of Engineers stated dams were worsening the problem § Began looking at non-­‐structural flood management § i.e. restoration of wetlands, limits on development in flood plains, policies discouraging conversion of wetlands for agriculture o Emergency management and planning, and other non-­‐structural approaches pertinent to successful flood management § DamAid and other preparedness measures Works Cited International commission on large dams. (n.d.). Retrieved from http://www.icold-­‐
cigb.org/GB/Dams/role_of_dams.asp World Commission on Dams. (2000). Dams and development : a new framework for decision-­‐
making : the report of the World Commission on Dams. London Sterling, VA: Earthscan. Rodrigues, A. S., Santos, M. A., & Rocha, F. (2002). Dam-­‐break flood emergency management system. Water Resources Management, 16, 489-­‐503. Yang, M., Qian, X., Zhang, Y., Sheng, J., & Shen, D. (2010). Assessing alternatives for sustainable management of a flood control dam . Procedia Environmental Sciences, 2, 98-­‐110. You, L., Li, C., Min, X., & Xiaolei, T. (2013). Review of dam-­‐break research of earth-­‐rock dam combining with dam safety management . Procedia Engineering, 28, 382-­‐388. Big Dams: Hydroelectricity Reid Esterson 1. What is hydroelectric power? a. Water that passes through a dam and pushes turbines to create a clean and renewable energy 2. Impacts a. Air quality-­‐ hydroelectric power poses no direct threat to the quality of neither air nor atmosphere1. Therefore no smog is produced, no chemicals released to make acid rain, etc. i. Indirect impact-­‐ if vegetation that has been submerged in water (generally along the banks) begins to rot, there will be methane (CH4) released into the air1 b. Emissions-­‐ the GHG and Carbon footprints of hydroelectricity are the cleanest and lightest out of all renewable and non-­‐renewable energy sources.2 Large dams have less of an impact than smaller ones in regards to CH4 emissions. c. Water quality-­‐ no water pollution occurs in creating hydroelectricity, no water is wasted, 100% renewable and clean. Unless water composition is anomalistically high, characteristic of very early dams, changes in water composition are negligible and should not be of primary concern when considering damming. If water is potable upon entry, water will be potable upon leaving the dam. 3. Finances a. The cheapest maintenance of all energy producers, and amongst the longest lifetimes. i. Average lifetime of dam 50-­‐100 years2 ii. Because of its cheap upkeep, governments may also reinvest the saved money into dam management and technology advancements iii. Great investment 4. Hydroelectricity’s potential a. In USA it makes up a total of 9% of energy usage1 i. Provides over 2/3 of Pacific NW’s energy 1. Produced energy for 28 million households àequivalent to 500 million barrels of oil1 ii. Washington State uses over 70% hydroelectric power3 b. Top five domestic producers: Brazil, Canada, China, Russia, and USA4 i. These 5 nations make up 52% of world hydropower51 c. Worldwide use of hydropower i. Hydropower in 150 countries 1. Concentrated in certain regions a. 2010: Asia-­‐Pacific makes up 32% of worldwide hydropower production5 1.
2.
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3.
4.
5.
1 "Hydroelectricity."
EPA. Environmental Protection Agency, 25 Sept. 2013. Web. 01 Feb. 2014.
"Advantages of Hydroelectric Power Production and Usage." Hydroelectric Power. Advantages, from USGS Water"Advantages
Hydroelectric
Power Production
Usage."
Hydroelectric
Power.
Science
School.ofUnited
States Geographic
Survey,and
23 May
2013.
Web. 01 Feb.
2014 Advantages, from USGS WaterScience School. United States Geographic Survey, 23 May 2013. Web. 01 Feb. 2014
"Hydropower." National Geographic. National Geographic, n.d. Web. 02 Feb. 2014.
"Which Countries Get the Most Energy from Hydropower? - Greenbang." Greenbang. Greenbang, 19 Apr. 2012. Web.
03 Feb. 2014.
"Use and Capacity of Global Hydropower Increases." Worldwatch Institute. Worldwatch Institute, 17 Jan. 2012. Web.
02 Feb. 2014.
b. 2010: Africa only 3% of worldwide hydropower production, but has highest undeveloped potential in world.5 2. 2010: 4 nations use 100% hydropower: Albania, Bhutan, Lesotho, Paraguay5 3. 2010: 15 nations use over 90% hydropower5 4. Iceland, NZ, and Norway have highest hydropower/capita5 d. $40-­‐45 billion invested in Hydropower in 20105 5. Pros a. Can reuse 100% of water123 b. No wasted or contaminated water (e.g. fracking, nuclear power) c. Low maintenance costs2 6. Cons a. Not suitable for all geographies, specific geographical requirements b. Expensive to build2 1.
2.
3.
4.
5.
2 "Hydroelectricity."
EPA. Environmental Protection Agency, 25 Sept. 2013. Web. 01 Feb. 2014.
"Advantages of Hydroelectric Power Production and Usage." Hydroelectric Power. Advantages, from USGS WaterScience School. United States Geographic Survey, 23 May 2013. Web. 01 Feb. 2014
"Hydropower." National Geographic. National Geographic, n.d. Web. 02 Feb. 2014.
"Which Countries Get the Most Energy from Hydropower? - Greenbang." Greenbang. Greenbang, 19 Apr. 2012. Web.
03 Feb. 2014.
"Use and Capacity of Global Hydropower Increases." Worldwatch Institute. Worldwatch Institute, 17 Jan. 2012. Web.
02 Feb. 2014.
Big Dams – Agricultural Irrigation Thomas Weston 51493104 Introduction Globally, agriculture is the largest consumer of freshwater, with irrigated agriculture accounting for 40% of global food production [1]. Since 1950, there have been huge increases in irrigated areas, facilitated by the construction of large dams and implementation of their associated projects [2]. Agricultural Irrigation and Big Dams Around 20% of the world’s agricultural land is irrigated, and agricultural irrigation accounts for about 40% of the world’s agricultural production [2]. Average crop yields for irrigated areas are 2.3 times higher than those from rainfed areas [4]. While only 16% of the world’s croplands are irrigated, these lands yield around 35% of the global harvest – demonstrating the elevated level of productivity that irrigated agriculture provides [3]. In developing countries, irrigation increases yields for most crops by 100 – 400% [3]. In the future, between half and two thirds of crop production will be attributed to irrigated lands [3]. Benefits of Big Dams to Agriculture The largest benefit of big dams to agriculture is the guarantee of a stable food supply, as they very effectively mitigate against the effects of drought; higher overall productivity is also achieved [4]. There are three main ways in which agricultural irrigation is less environmentally degrading than other irrigation strategies (particularly rainfed irrigation) – increased CO2 sequestration, reduced N2O emissions and more efficient fertilizer use [4]. Agricultural irrigation is able to meet increasing food need, with increased food production. This increasing need is due to several factors – increasing global population, decreasing freshwater supply, progressively changing climate, the conversion of farmland to other uses (primarily residential), and the increasingly poor quality of the farmland itself [4]. On a smaller scale, primarily within developing countries, agricultural irrigation provides greater food security and nutrition at the household level; between 1970 and 1995, nutritional levels increased by 14% in India and 30% in China, two of the largest builders of irrigated dams [2]. Drawbacks of Big Dams to Agriculture There are, however, various drawbacks to agriculture, that large dams create. The first is an inefficient usage of water, which results from the belief that the dam will always provide enough [2]. The second is the inadequate maintenance of physical streams [2]. The third is the issue of waterlogging and salinity [2]. The fourth is the loss of annual silt and nutrient replenishment, in addition to the loss of fertility of formerly productive floodplain soils [2]. The final drawback is that in terms of the economy, large irrigation schemes often lead to the production of more cash crops and fewer food crops [2]. While this is a logical decision for commercial farmers, people who either do not participate in these projects, or are otherwise marginalized due to dam construction, may face higher food prices and decreased food security [2]. Conclusions In order to combat a growing global population and increased environmental pressures, agricultural irrigation enabled by and related to large dams, is necessary. However, various changes need to be made to existing strategies. Improved basin and system level management is needed, and other irrigated agriculture strategies (excluding dams) need to become more efficient (eg. drip irrigation) [2]. The issue of salinity also needs to be addressed, as this problem will only grow with a warming climate [2]. The performance and productivity of existing irrigation systems need to be improved [2]. Alternative supply-­‐side measures need to be utilized, in addition to large-­‐scale projects, with the purpose of supplementing, rather than replacing these larger and more dominant projects [2]. Bibliography 1. United Nations World Water Assessment Programme. (2012). World Water Development Report 4 (WWDR4) Facts and Figures. United Nations Educational, Scientific and Cultural Organization. 2. World Commission on Dams. (2000). Dams and Development: A New Framework for Decision-­‐Making. London, UK. Earthscan Publications Ltd.. 3. Food and Agriculture Organization of the United Nations. (1996). Water and Food Security. Natural Resources Management and Environment Department. 4. Dowgert, Michael. (2010). The Impact of Irrigated Agriculture on a Stable Food Supply. Proceedings of the 22nd Annual Central Plains Irrigation Conference, Kearney, NE., February 24-­‐25, 2010. Eva Crego Liz
Panel on Big Dams: Case Study - High Aswan Dam (HAD)
The case study of the High Aswan Dam (HAD) has been chosen to portray how the different effects
that the construction of a large dam may entail both beneficial and harmful, come together in a real
case. This presentation aims not only to provide a more or less thorough inventory of benefits and
impacts caused by the HAD, but also to analyze how the decision to build the dam was made and what
lessons can be learned. Therefore, the analysis framework proposed by the World Commission on
Dams (WCD) has been adopted.
The decision to build the HAD responded to the prevailing “development” and “water management”
paradigm at the time the dam was planned and built. There was a vision of development as economic
growth achievable through increased agricultural production and industrialization. In this context,
water management was exclusively oriented to match the increasing demand. Under this paradigm,
technical and economic factors outweighed environmental and social impacts in the decision. The
political context of the time also made difficult a more global assessment at a basin level.
The HAD has fulfilled the expectations placed on it, but the economic and social benefits of the dam
like flood and drought protection, hydropower production, perennial agriculture among others, have
come along with many other harmful environmental, social and economic impacts like biodiversity
loss, water quality deterioration, human health issues, loss of traditional livelihoods, people
displacement. All these facts unveil the failure of the conventional cost/benefit approach based on
physical and economic variables to account for the environmental and socioeconomic effects that the
construction of a big dam may cause.
This brings us to the new framework for decision-making that the WCD proposes on its Final Report
(WCD, 2000), where “[…]a participatory multi-criteria assessment that gives the same significance to
social and environmental aspects as to technical, economic and financial aspects and covers the full
range of policy, programme, and project options” is recommended. This new assessment framework,
along with demand-focused strategies and a basin approach might have led to different outputs, or at
least to different options to be considered with regard to water resources management in Egypt.
References:
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Fahim, H.M., 1981. Dams, People and Development. The Aswan High Dam Case. Pergamom Press,
New York, 187 pp.
Kashef, A.I., 1981. Technical and Ecological Impacts of the High Aswan Dam. Journal of Hydrology,
53, pp. 73-84
Khagram, S., 2004. Dams and Development. Transnational Struggles for Water and Power. Cornell
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Said, R., 1993. The River Nile. Geology, Hydrology and Utilization. Pergamon Press, New York, 320
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WCD, 2000. Dams and Development. A New Framework for Decision-Making. The Report of the
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