Regional Approach to Climate Change Exigencies: The Ecosystem,
Streamflow and Fisheries Management Perspectives
1
Albelee A. Haque, 2Shiba P. Kar, 3Xin Yuan and 4Farhana Sharmin
1
Bangladesh Environment Network (BEN)- Email:albelee_haque@yahoo.com
Pennsylvania State Univ., 235 Forest Resources Bldg., Univ. Park, PA 16802 - Email:shiba.kar@psu.edu
3
UMass Amherst, Dept of Civil- Environmental Engg., Amherst, USA; 4Practical Action- BD, Dhaka 1205.
2
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 three-prong
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
depletion of 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 an ecosystem and socioeconomic standpoint. 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.
I. 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 [4]. 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 [1] due to GCM predicted global climate change [13]-[15]. 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 [1]. Deltas need sediment subsidies [12] and natural streamflow can
tremendously help with adaptation. This paper suggests region-specific solutions. It asserts watershedbased ecosystem approach and human adaptation to meet the climate change exigencies. Also technologybased effluent treatment plants (ETP) can help revive fisheries and reduce river pollution due to the dual
Figure 1. Study Area – Bangladesh delta
Courtesy: BD Assoc. of Delaware Valley, USA.
impact of fast industrialization and climate impact. 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 [13] and to go forward in realizing economic growth. Although our
main focus is the 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.
II. HYDROPOWER DAMS, CLIMATE AND FISHERIES IMPACT
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 [2]-[3] 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 [1]. Kromer-Baker and Baker, 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 [20]. 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 [5]. 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 [6]. 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 [17].
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 [21]. 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 shoreline with
vegetation and reforestation, cyclone warning and evacuation will constitute better strategic planning to
meet the fisheries management, ecosystem and habitat protection challenges (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
2
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 [7]. 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. 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.
III. 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 [8]-[9]. High counts of dinoflagellate plankton 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 (blue-green algae), including
Cylindrospermopsis, Aphanizomenon and Lyngbya. Artificial circulation can alter algal biomass and
species composition shifting phytoplankton dominance to green algae and diatoms [11][16]. Aeration can
also work by creation of suitable zooplankton refuge and enhancement of phytoplankton grazing potential,
most notably by the large-bodied Daphnia [10][16]. Biomass of toxin forming cyanobacteria including
Microcystis aeruginosa was minimized in Lake Nieuwe Meer (The Netherlands) and Lake Palmdale
(California) by artificial circulation, with a shift to less harmful or edible green algae [10]-[11].
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
Table 1. Teesta River Long Term Flow Characteristics (Kaunia Station) and EF Requirements (Mullick et al. 2010)
3Observed
Seasons
Period
Flow requirements
Tennant Method
mean monthly
(% of 1MAF)
HF
LF
flow
(m3/s)
(m3/s)
(m3/s)
HF
*1967-1990
1970
Flushing flow (200%)
1772
1772
**1991-2000
2140
Optimum range (60-100%)
532-886
532-886
***2001-2006
1548
Excellent (50% at HF, 30% at LF)
443
266
Good (40% at HF, 20% at LF)
354
177
LF
*1967-1990
169
Fair/degrading (30% at HF, 10% at
266
89
**1991-2000
152
LF)
< 89
< 89
***2001-2006
80
Poor (10%) to severely degraded
<10%
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
(December – March) based on Tennant [19] 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 Bangladesh has one barrage each) mean annual flow (MAF) calculation using 40year (1967-2006) data shows a declining trend, with severe low flow impact for post-barrage II period [18].
Thus, dam removal and adequate wastewater treatment are 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 [7]. Recycle of treated
effluents for agriculture/industrial process water and discharge of very low nutrient waters to the rivers,
3
lakes and estuaries can protect freshwater and marine fisheries and ecosystem health from human
watershed activity related excess nutrients and toxic pesticides and/or domestic wastewater discharges.
IV. 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 [13]. 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
salinity issues linked to dams and GCM predicted climate destabilization [1][14] and rapid urbanization
[16] 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 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.
REFEENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
K. M. Elahi, M. T. Sikder. Mega dams in the Himalayas: An assessment of environmental
degradation and global warming. Proceedings of ICEAB10 - BENJP.
University of Kitakiushu – Japan, Sep 4, 2010.
M. S. Moran, R. M. Cushman, S. B. Gough, R. B. Craig. 1980. Sourcebook of Hydrol. and Ecol.
Features: Water Res. Regions of the Conterminous US. Ann Arbor (MI): Ann Arbor Sc.
[BEN] 2009-2010. Newsletter, Vol. 5, No. 29; Vol. 6, Nos. 4-5. http://www.ben-global.org.
J. B. Anderson. 2007. Ice sheet stability and sea-level rise: Science, v. 315, p. 1803-1804.
Email -johna@esci.rice.edu.
M. A. Anderson. Influence of pumped-storage hydroelectric plant operation on a shallow
polymictic lake: Predictions from 3-D hydrodynamic modeling. Dept. of Env. Sciences. Univ. of
California, Riverside, CA 92521.
C. A. Rodriguez, K.W. Flessa, D. L. Dettman DL. 2001. Macrofaunal and isotopic estimates of the
former extent of the Colorado River Estuary, upper Gulf of California, Mexico. Journal of Arid
Environments, Vol. 49, p 183 -193.
D. A. Haith. 1975. Integrated systems for power plant cooling and wastewater management.
In: Jewell W. J. (ed). Energy, Agriculture and Waste Management. Proceedings of the 1975
Cornell Univ. Agri. waste mgmt. conf. Ann Arbor (MI): Ann Arbor Science Publishers Inc.
H. W. Paerl, J. Huisman. 2008. Blooms like it hot. Science, Vol. 320, April 4, 2008:57-58.
C. S. Reynolds. 2006. Ecology of Phytoplankton. Cambridge Univ. Press.
H. K. Hudnell, C. Jones, B. Labisi, V. Lucero, D. R. Hill, J. Eilers. 2010. Freshwater harmful
algal bloom suppression with solar powered circulation (SPC). Harmful Algae, 9:208-217.
G. D. Cooke, R. H. Kennedy. 2001. Managing drinking water supplies. Lake Reserv
4
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
Manage. 17(3):157-174.
G. Cole. 1988. Textbook of Limnology. 3rd ed. Arizona State Univ. (AZ). US.
K. Hayhoe et al. 2007. Past and future changes in climate and hydrological indicators in the US
Northeast, Clim. Dynam., 28: 381-407.
N. Stern. 2006. Stern review executive summary, New Economics Foundation, p 195.
[UN] United Nations. 2007. World Urbanization Reports: The 2007 Revision.
K. J. Wagner. 2010a. Recognizing, understanding and controlling nuisance freshwater algae. A
Lake Steward Workshop – sponsored by the North American Lake Management Society
(NALMS), New England Ch. Worc. State College, Worcester, MA. USA. June 11-12, 2010.
R. G. Wetzel. 2001. Limnology: lake and river ecosystems. San Diego, Academic Press.
R. A. Mullick, M. S. Babel and S. R. Perret. Flow characteristics and environmental flow
requirements for the Teesta River, Bangladesh. ICEAB10 (BENJP publication), p 159-162.
L. Tennant. Instream flow regimes for fish, wildlife, recreation and related environmental
resource. Fisheries. vol. 1, 1976. p 6-10.
K. Kromer-Baker, A. Baker. 1981. Seasonal succession of the phytoplankton in the upper
Mississippi River. Hydrobiol. 83:295-301.
T. M. Conry. 2010. Historical, current, and future economic benefits and costs relating to Lake
Waco, Texas. Lake Reserv Manage. 26:80-84.
5