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Regional Approach to Climate Change Exigencies: The Ecosystem, Streamflow and
Fisheries Management Perspectives
Albelee A. Haque
Bangladesh Environment Network (BEN)- Email:[email protected]
Shiba P. Kar
Pennsylvania State Univ., 235 Forest Resources Bldg., Univ. Park, PA 16802, US - Email:[email protected]
Xin Yuan
Impact Environmental Consulting, Inc., 170 Keyland Ct., Bohemia, NY 11716, US
and
*
Farhana Sharmin
Practical Action - BD, House # 12/B, Rd # 4, Dhanmondi R/A, Dhaka 1205, Bangladesh
Email: [email protected]
ABSTRACT
The purpose of this paper is to highlight the importance of a regional and watershed-based
approach necessary to meet climate change exigencies in the fore of Bangladesh (BD). We present a threeprong management decision tree model embracing ecosystem function, natural streamflow and fisheries
revival. The indigent populations of the Bengal delta are facing malnutrition, water shortage and related
ecosystem services deprivation threats due to global climate change, as predicted by general circulation
models (GCM) and rapid industrialization dependent upon fossil fuel or hydropower dam construction.
The result of unplanned growth and industrialization without considering ecosystem impact is essentially
environmental degradation and deleterious impact on natural resources, such as, clean water and
freshwater fisheries. The mega hydropower dams on international rivers by co-riparian nations without
introspection into ecosystem consequences can impede or impair streamflow and other life-giving
characteristics of the energetic rivers of the Bengal delta. The large hydropower dams are, therefore,
untenable from ecosystem and socioeconomic standpoints. The importance of natural streamflow cannot be
stressed enough. Human manipulation of riverine systems by dams (unless ecologically scaled) can
exacerbate climate variability and iniquity and hinder efforts to bolster natural resource protection. A
region-specific approach including water diplomacy is necessary to resolve the ecosystem issues. Attention
to these factors are particularly important to minimize an urbanization nightmare caused by likely influx of
climate refugees from coastal areas of low topographic relief.
INTRODUCTION
Climate change awareness is an indispensable part of natural resources management strategies for
many nations in different parts of the world including the Gulf Coast estuaries along Texas coast in the
United States (US) susceptible to changes in sediment supply (Anderson, 2007). Our study focuses on
Bangladesh (BD) that belongs to the Ganges Brahmaputra Meghna basin. The Bengal delta and especially
BD is one of the most vulnerable geographic areas due to GCM predicted global climate change (Stern
2006, IPCC 2007). It is notable that the Tibetan glaciers that feed important river systems in South Asia
receded 196 sq KM (1/4 the size of New York City) over the past 40 years (Elahi and Sikder, 2010). Deltas
need sediment subsidies (Cole, 1988) and natural streamflow can tremendously help with adaptation. This
paper suggests region-specific solutions. It asserts watershed-based ecosystem approach and human
adaptation to meet the climate change exigencies. Also technology-based effluent treatment plants (ETP)
can help revive fisheries and reduce river pollution due to the dual impact of fast industrialization and
climate effect. Indifference to the forces of nature and ecosystem functionality with outmoded policy and
management style cannot help with efforts to adapt to the climate change phenomenon in this century and
to go forward in realizing economic growth. Although our main focus is BD delta (Fig. 1), ecological data
from other parts of the world with similar geographic features are also referred to as they are clearly
relevant, given the global nature of climate change. The average tidal level in BD coast (higher than global
rate) may worsen in future with sea level rise to about 7 mm/yr due to the virtual elimination of Greenland
Ice sheet (IPCC 2007) leading to the submergence of more landmass and result in millions of climate
refugees (Myers, 2002), who will then try to move to the urban centers.
Figure 1. Study Area – Bangladesh delta.
Courtesy: BD Assoc. of Delaware Valley, USA.
HYDROPOWER DAMS, CLIMATE AND FISHERIES IMPACT
Dams are linked with urbanization in many cases. Hydropower dam on rivers causing nutrient rich
riparian soils that are responsible for proliferation of algae and rooted aquatic plants (macrophyte)
ultimately becomes a human induced natural condition degrading water quality and limiting beneficial
ecosystem uses (fishing, bathing, boating). The worst impact on ecology/aquatic biota of the southwestern
US and southeastern BD (Cushman et al. 1980; Sikder and Elahi, 2010) occurred from extensive damming
of the US rivers and India’s Farakka barrage construction, respectively. These projects changed either flow
characteristics or post-dam salinities and also favored species that prefer slower velocities (Cushman et al.
1980). Kromer-Baker and Baker (1981), who studied the effects of temperature and current discharge,
noted that algal concentrations increased up to 40-fold the levels of the 1920s since the installations of
locks/dams in the Mississippi River (US), south of the Minneapolis-St. Paul metropolitan area. It is notable
that some researchers found up to 40% mortality of larval fish (e.g., catfish) entrained during pumping due
to hydroelectric power plant operation in North America (Anderson, 2010). Hoover dam changed
hydrodynamic characteristics creating an inverse estuary and artificially increased salinities toward the
mouth of the Colorado River; many fish and aquatic species adapted to natural flooding decimated
(Rodriguez et al. 2001). Also shift in regional climate pattern might be due to alteration of large riverine
systems by dams and diversions, with major increases in surface water evaporation rates (Wetzel, 2001).
Removal of dam to restore salmon habitats and spawning, among other things, for example along
the Columbia and Snake Rivers (I. Mahbubul, US Environmental Protection Agency - Region 10, pers.
comm., April 2009) is becoming the new approach in the US. India and China may benefit from the US
experience and opt for ecologically sustainable industrialization. On the other side, BD may not have to
face water quality degradation because of the mega dams built by co-riparian nations. Lake and reservoir
management for flood storage (e.g., Lake Waco in central Texas contributed >$258 million in flood
damage prevention since 1964) has gained attention of authorities in various states in the US (Conry,
2010). While hydroelectric dams for power and irrigation can worsen water quality and quantity problems,
flood control dams only provide a pseudo sense of security when water levels rise. Stabilizing coastal
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shoreline with vegetation and reforestation, cyclone warning and evacuation will constitute better strategic
planning to meet the double challenge of fisheries management and ecosystem protection or habitat
preservation in the face of climate change (see Fig. 2).
Climate Exigency (regional
involvement)
Riparian Vegetation
(prevents erosion)
– fisheries protection
Effluent Treatment Plants
- disinfected/treated
wastewater return flows
- low flow augmentation
Ecosystem Protection
- dam removal/ecologically
scaled hydropower dams
- unstated ecosystem cost
consideration
Figure 2. Management Decision Tree to Address Climate Change Exigencies
Increased metabolism at higher temperatures leads to greater oxygen demand with accelerated
decomposition at the lake-bottom and rapid oxygen depletion (may lead to death of fish and aquatic
species). Setting apart the climate variables (temperature, salinity), artificially raised temperatures and low
dissolved oxygen due to thermal discharge from hydroelectric plants can also affect fish and aquatic species
diversity (Haith, 1975). Fish and rice are considered staples for agrarian BD. A country that has substantial
population living below poverty line (suffering from malnutrition) could benefit from any improvements to
its freshwater fisheries. Moreover, the knowledge of temperature acclimation and individual adaptation to
environmental changes due to damming (obstruct fish passage) of rivers and climatic conditions can help
with better management models and decision tree (Fig. 2) relative to ecosystem improvement and fisheries
protection. The idea of integrated water resources management (IWRM) has gained support and
redoubtable credence during the last 15 years as the necessity to integrate or link engineering projects and
the natural science of water to socio-cultural context is undeniable, especially due to the interconnectedness
of the various domains of water resources management (Braga, 2001; McDonnell, 2008).
ECOSYSTEM PROTECTION AND FLOW CHARACTERISTICS
Adaptive watershed management and technology can help us meet the climate change exigencies.
Low flow and untreated or partially treated wastewater discharges promote algal accumulation and toxic
blooms. Temperature plays a dominant role in influencing algal community composition and occurrence of
algal toxins like the cyanotoxins in freshwater subject to high phosphorus load (Reynolds, 2006; Paerl and
Huisman, 2008). High counts of dinoflagellate plankton (may be triggered by sewage derived nitratenitrogen from watershed sources) are toxic in saltwater, but rarely toxic in freshwater. Cylindrospermopsin
is a hepatotoxin (known to impact drinking water supplies in tropical/sub-tropical areas) produced by
numerous strains of cyanobacteria (i.e., blue-green algae) including Cylindrospermopsis, Aphanizomenon
and Lyngbya. Artificial circulation can alter algal biomass and species composition shifting algal
dominance to green algae and diatoms (Cooke et al. 2001; Wagner, 2010). Aeration can also work by
creation of suitable zooplankton refuge and enhancement of grazing potential, most notably by the largebodied Daphnia (Hudnell et al. 2010, Wagner, 2010). Biomass of toxin forming cyanobacteria including
Microcystis aeruginosa was minimized in Lake Nieuwe Meer (The Netherlands) and Lake Palmdale
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(California) by artificial circulation, with a shift to less harmful or edible green algae (Cooke et al. 2001;
Hudnell et al. 2010). Thus, appropriate levels of wastewater treatment (before discharge) and/or in-lake
aeration can offset the temperature effect and help maintain desirable water quality in lakes/rivers.
Table 1. Teesta River Long Term Flow Characteristics (Kaunia Station) and EF Requirements
(Mullick et al. 2010)
Seasons
HF
LF
Period
3Observed
*1967-1990
**1991-2000
***2001-2006
*1967-1990
**1991-2000
***2001-2006
mean monthly
flow
(m3/s)
1970
2140
1548
169
152
80
Flow requirements
(% of 1MAF)
Tennant Method
HF
(m3/s)
LF
(m3/s)
Flushing flow (200%)
Optimum range (60-100%)
Excellent (50% at HF, 30% at LF)
Good (40% at HF, 20% at LF)
Fair/degrading (30% at HF, 10% at
LF)
Poor (10%) to severely degraded
<10%
1772
532-886
443
354
266
< 89
1772
532-886
266
177
89
< 89
HF – High flow season, LF – Low flow season; *Pre-barrage, **Post-barrage I, ***Post-barrage II;
1MAF – mean annual flow based on pre-Gazaldoba (India) and Dalia-Doani (BD) barrage construction for irrigation;
2FDC Method flow requirements: HF (50th percentile) 1280 – 2180 m3/s and LF (90th percentile) 108-151 m3/s.
3Data
source: Bangladesh Water Development Board; m3/s – cubic meter/sec
BD is in urgent need of both technology- and watershed-based ecosystem protection measures for
locally controllable pollution. Adequate wastewater collection/conveyances and treatment facilities are
essential to protect the rivers and lakes/ponds. Also industrial pretreatment is necessary before discharging
into sewers to avoid toxic inputs into publicly owned treatment works. Treated wastewater return flows
during winter can compensate for drought flow. For example, environmental flow (EF) requirements for
the Teesta in drought-prone northern BD (with significant agricultural potential) for low flow period
(December – March) based on Tennant (1976) and flow duration curve (2FDC) range between 89–177 m3/s
and 108-151 m3/s, respectively (Table 1, Fig. 1) to maintain good to fair ecosystem condition. The pre- and
post-barrage (India and BD has one barrage each) mean annual flow (MAF) calculation using 40-year
(1967-2006) data shows a declining trend, with severe low flow impact for post-barrage II period (Mullick
et al. 2010). Dam removal (when feasible after environmental impact assessment) and adequate wastewater
treatment are both needed to improve ecosystem services.
Furthermore, agricultural application of treated sewage sludge is common in the western countries.
This will reduce the need for energy-demanding chemical fertilizers and pesticides (Haith, 1975) and
curtail fossil fuel dependency. Renewable energy sources (e.g., biofuel) and high energy-efficiency are
necessary antidotes to avoid the precarious consequences of rapid industrialization and hydropower dams.
Efficient use of irrigation water (by use of perforated tubing as opposed to spray irrigation) can also help
reduce evaporation loss and water waste eliminating the need for diversionary structures (BEN 2009) that
can create low flow problems in lower reaches of a river. Recycle of treated effluents for agriculture and
industrial process water and discharge of very low nutrient waters to the rivers, lakes and estuaries can
protect freshwater and marine fisheries and ecosystem health from human watershed activity related excess
phosphorus and toxic pesticides and/or domestic wastewater discharges.
SUMMARY AND RECOMMENDATIONS
While hydroelectric dams for power/irrigation can worsen low streamflow problems, flood control
dams provide a pseudo sense of security. Suffice it to say, a paradigm shift embracing the ecosystem
approach that calls for uninterrupted streamflow and critical regional cooperation (including diplomatic
missions) is needed to avoid unnecessary damming or diversions of the shared international rivers. The
Bengal delta and the entire region could benefit from natural river flows and sediment subsidies. ETPs and
treated wastewater return flows to rivers can also help with environmental flow requirements, with
improved ecosystem services during low flow seasons in drier parts of BD. Increased river pollution and
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salinity issues linked to dams and GCM predicted climate destabilization (Rodriguez et al. 2001; Elahi and
Sikder, 2010, Mullick et al. 2010) as well as rapid urbanization (UN 2007) can be resolved at the local and
regional scales with improved knowledge and understanding of ecosystem function. This paper is a
condensed version of an elaborate research based on extensive literature review. Low flow augmentation
may be necessary to overcome the climate impediment for future river restoration projects in many areas of
the world. The infelicitous end result of excessive damming is disappearance of ecosystem service benefits
(fishing, boating) to the affluent and poor alike. The use of IWRM in environmental, social, economic and
cultural impact assessment of engineering structures is the much needed modern approach. The authors
recommend greater collaboration among lake and river management experts, NGOs and public officials
and a congruent water-energy-ecosystem policy formulation under the same governmental authority.
DISCLAIMER
Opinions are the authors’ and may not reflect the policy, support or endorsement by any agency
ACKNOWLEDGMENTS
We appreciate the comments from three anonymous reviewers and Prof. Saleh Tanveer, Ohio
State University, OH, USA, which improved the preliminary draft. Prof. William Moeller, Ph.D., P.E.,
University of Massachusetts Lowell – Water Resources Department and Prof. Farida Khan, co-director of
the Center for International Studies, Wisconsin University, WI, USA encouraged to write and publish.
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