Why river basin Prof. R. Nagarajan, CSRE , IIT Bombay GNR 624 : - - PowerPoint PPT Presentation

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Lesson 3

Why river basin

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

• Freshwater ecosystems are the rivers, streams, lakes, ponds, groundwater, cave

water, springs, floodplains, and wetlands (bogs, marshes, and swamps) that provide water for drinking, sanitation, agriculture, transport, electricity generation and recreation.

• Physical

alteration, habitat loss and degradation, water extraction,

• ver-

exploitation, pollution and the introduction of invasive species threaten the planet’s freshwater ecosystems and their associated biological resources.

• The most threatened rivers. Instead, it captures the diverse social, hydrological,

climatic and biological factors which threaten the integrity of major watersheds

• Rivers suffering from existing threats and those which are relatively intact but under

imminent danger from emerging threats. It is important to note that most river basins suffer from multiple threats that often compound each other.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

• Dams and other infrastructure have caused the fragmentation of 60% of the large river

systems in the world.

• Only 64 of the world’s 177 large rivers (1,000 km and longer) remain free-flowing, unimpeded

by dams or other barriers.

• There are more than 45,000 large dams in over 150 countries.
• About 1,500 are currently under construction.
• Some 40 to 80 million people have been displaced by dams worldwide.
• But not all dams are bad, it depends how and where they are built.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

The world’s Longest rivers River name Continent Total length Nile Africa 6695 Km Amazon South America 6400 Km Yangtze Asia 6300 Km Mississippi-Missouri-Red Rock North America 5970 Km Yeisey-Angara Asia 5550 Km Yellow River Asia 5464 Km Ob’-Irtysh Asia 5410 Km Rio Parana-ril grande South America 4500 Km Amur-shilka Asia 4416 Km Lena Asia 4400 Km Congo Africa 4374 Km Mackenzie-Peace-Finlay North America 4241 Km Mekong Asia 4200 Km Niger Africa 4180 Km

Melt waters of glaciers - Rhone (France), lakes, e.g. Nile (Africa), springs, e.g. Thames (England) Regions of steady rainfall - Zaire (Africa). End at in the sea Amazon (Atlantic), the Niger (Gulf of Guinea) and the Indus, (Arabian Sea). Sometimes the mouth could be in a lake, e.g. Volga (Caspian), or in a swamp, e.g. Chari River (Lake Chad).

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Source courtesy: gangaaction.org

River impacts assessed by

• dams and infrastructure,
• excessive water extraction
• climate change,
• invasive species,
• ver-fishing,
• pollution.

Most endangered rivers that affects human population are:

• Salween
• La Plata
• Danube
• Rio Grande
• Ganges
• Murray-Darling
• Indus
• Nile
• Yangtze
• Mekong

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Global Water Challenges

Ratio of maximum annual flow to minimum annual flow for selected rivers 15.5 MURRAY AUSTRALIA 4705.2 DARLING AUSTRALIA 54.3 HUNTER AUSTRALIA 16.9 ORANGE SOUTH AFRICA 3.9 POTOMAC USA 2.4 WHITE NILE SUDAN 2.0 YANGTZE CHINA 1.9 RHINE SWITZERLAND 1.3 AMAZON BRAZIL

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

River Facts

• An unsettling number of large rivers—including the Colorado, Rio Grande,

Yellow, Indus, Ganges, Amu Darya, Murray, and Nile—are now so over tapped that they discharge little or no water to the sea for months at a time.

• China is proceeding with a massive $60 billion project to transfer water from

the Yangtze River Basin in the south to the water-short north. If completed it would be the largest construction project on Earth and would transfer 1.5 trillion cubic feet (41.3 billion cubic meters) of water per year—a volume equal to half that of the Nile River.

• After enduring 19 flood episodes between 1961 and 1997, Napa, California,
• pted to restore the Napa River floodplain for $366 million, instead of the more

conventional flood-control strategy of channelizing and building levees.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Main threats to river basins Construction of large dams and physical alterations of river flow by straightening and deepening. River course disrupt the natural flooding cycles, reduces flows, drains wetlands, cuts rivers off from their floodplains, and inundates riparian habitats, resulting in the destruction of species, the intensification of floods and a threat to livelihoods in the long term. Deforestation and loss of natural habitats including wetlands for urban, industrial or agricultural use reduces natural flood control and destroys the habitats used by fish, water birds’ breeding, feeding and migrating. Excessive water abstraction for agricultural irrigation, domestic consumption and urban/industrial use involve pumping too much water from underground supplies, or long distance transfers of water from one basin to a neighbouring river basin result in dried-up river beds and wetlands. Ecological and economic value of freshwater systems damaged or destroyed by such technical fixes are not taken properly into account. Pollution is caused by runoff from agricultural chemicals, poorly-managed / out-of-date industrial processes, and lack of adequate treatment for sewage and other urban waste. This results in water unfit to drink, massive fish kills, and loss of underwater plants. Long-term changes in rainfall, river flow and underground water supplies due to climate change aggravates the short-sighted land-use planning that affects all sectors of human society. The rate and scale of these impacts are

• nly set to grow.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management Threats to rivers

• Salween (ASIA) faces heavy threat from damming, the Danube (Europe) from navigation

infrastructure, and La Plata (South America) from both.

• Rio Grande (USA) and the Ganges face very similar problems from over-extraction for increasing

irrigation and domestic consumption.

• Indus faces threat from climate change because of its high dependency on glacier water. The Nile

basin is very sensitive to increases in temperature because of its high rate of evaporation.

• Invasive species is a plant or animal that is intentionally or unintentionally introduced to a region in

which it did not naturally evolve, and where in its new environment, it grows to out-compete native species and communities. Murray-Darling (Asia-Pacific)

• Mekong (Asia), the importance of fisheries for human subsistence cannot be understated, but this

naturally bountiful resource is not being managed for future use.

• Freshwater ecosystems naturally filter and purify water. However, this ability is impaired by excessive

pollution and habitat degradation (Yangtze (Asia)

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Threats to

• Colorado River in the Grand Canyon. - A proposed industrial-scale construction project threaten the Grand Canyon’s wild nature and

unique experience that belongs to every American

• Columbia River- Outdated dam operations are putting healthy runs of salmon and other fisheries at risk.
• Holston River- Toxic chemicals from the Holston Army Ammunition Plant are putting local water supplies and the community’s health at risk.
• Smith River - A proposed copper mine could harm a nationally-renowned wild trout fishery.
• Edisto River - Excessive agricultural water withdrawals are putting water supply, water quality, fish and wildlife habitat, and recreation at risk.
• Chuitna River - A proposed mine threatens to destroy 30 square miles of irreplaceable wild river habitat.
• Rogue-Smith Rivers - Strip mining, road construction, and metal processing would devastate this fragile, precious wild area.
• St Louis River - Mining could destroy or degrade thousands of square miles of pristine forested wetlands and streams.
• Harpeth River- Sewage pollution and water withdrawals are putting clean water, fish and wildlife, and recreation at risk.
• Pearl River - A new dam threatens to ruin healthy wetlands and wildlife habitat

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management Summary of Threats

River basin Corresponding Threat Salween - Nu Infrastructure - Dams Danube Infrastructure - Navigation La Plata Infrastructure - Dams and Navigation Rio Grande - Rio Bravo Water Over-extraction Ganges Water Over-extraction Indus Climate Change Nile-Lake Victoria Climate Change Murray-Darling Invasive Species Mekong - Lancang Over-fishing Yangtze Pollution

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Drainage Basins

• A drainage basin is a region of land where water from rain or snow melt drains downhill into a

body of water, such as a river, lake, dam, estuary, wetland, sea or ocean. It includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels.

• Drainage basin acts like a funnel - collecting all the water within the area covered by the basin and

channelling it into a waterway.

• Each drainage basin is separated topographically from adjacent basins by a ridge, hill or mountain,

which is known as a water divide or a watershed. Evolutionary studies of drainage systems may afford valuable information about the denudational history of an area.

• Reconstruction of the initial form of a river system in order to gain evidences of the nature and

mode of origin of the land surface on which that system began its existence.

• Drainage divide - a ridge or strip of high ground dividing one drainage basin from another. It

determines into which basin precipitation flows. Interfluves are the upland between tributaries.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Rivers are managed or controlled to be useful and less disruptive to human activity.

• Dams or weirs may be built to control the flow, store water, or extract energy.
• Levees may be built to prevent run-off of excess river water in times of flood.
• Canals connect rivers to one another for water transfer or navigation.
• River courses may be modified for navigation, or straightened to increase the

flow rate.

• Rivers have played an important and life-sustaining role in human societies for

thousands of years. World's great cities sit on the bank of a great river.

• It is used them as a source of water, for food, transport, recreation, power, and

as a means of disposing of waste.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

• Stop polluted runoff and sewage spills, onto rivers and streams safer for drinking, swimming, fishing

and boating.

• Secure reliable and predictable supplies of clean water by protecting the water flow in rivers.
• Remove outdated and unsafe dams, and improving the operations of hydropower dams.
• National River Clean up offers support to individuals and organizations interested in clean up on their

local river.

• The impacts of climate change will hit rivers first and worst. Help communities to build resilience in

the face of increased droughts, floods, and waterborne diseases as their strongest defence.

• Improve the flood protection and boost river health
• Creating blue trails across the country to help people discover rivers and provide connections

between urban and rural communities and the great outdoors.

• Protect our nation’s last, best free-flowing rivers with Wild and Scenic River designations.

Efforts in protecting rivers

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Observed effects of climate change and its observed/possible impacts on water services Observed effect Observed/possible impacts

Increase in atmospheric temperature

• Reduction in water availability in basins fed by glaciers that are shrinking, as observed in some cities along the Andes in South America

Increase in surface water temperature

• Reductions in dissolved oxygen content, mixing patterns, and self purification capacity
• Increase in algal blooms

Sea-level rise

• Salinisation of coastal aquifers

Shifts in precipitation patterns

• Changes in water availability due to changes in precipitation and other related phenomena (e.g., groundwater recharge,

evapotranspiration) Increase in inter-annual precipitation variability

• Increases the difficulty of flood control and reservoir utilisation during the flooding season

Increased evapotranspiration

• Water availability reduction
• Salinisation of water resources
• Lower groundwater levels

More frequent and intense extreme events

• Floods affect water quality and water infrastructure integrity, and increase fluvial erosion, which introduces different kinds of

pollutants to water resources

• Droughts affect water availability and water quality

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Likelihood trends based on projections for 21st century using SRES scenarios

• 1. Heavy precipitation events: frequency increases over most areas
• Very likely Damage to crops; soil erosion; inability to cultivate land due to waterlogging of soils
• Adverse effects on quality of surface and groundwater; contamination of water supply; water scarcity may be

relieved

• Increased risk of deaths, injuries and infectious, respiratory and skin diseases
• Disruption of settlements, commerce, transport and societies due to flooding; pressures on urban and rural

infrastructures; loss of property

• 2. Area affected by drought increases
• Likely Land degradation, lower yields/crop damage and failure; increased livestock deaths; increased risk of wildfire
• More widespread water stress
• Increased risk of food and water shortage; increased risk of malnutrition; increased risk of water- and foodborne

diseases

• Water shortages for settlements, industry and societies; reduced hydropower generation potentials; potential for

population migration

• 3. Intense tropical cyclone activity increases
• Likely Damage to crops; wind throw (uprooting) of trees; damage to coral reefs
• Power outages causing disruption of public water supply
• Increased risk of deaths, injuries, water- and foodborne diseases; post-traumatic stress disorders
• Disruption by flood and high winds; withdrawal of risk coverage in vulnerable areas by private insurers; potential

for population migrations; loss of property

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Natural and anthropogenic drivers of water balance:

• Climate change, which has direct consequences on precipitation (amount and timing) and on
• temperature. Temperature and air humidity rates influence evapotranspiration and the amount
• f precipitation impacting surface runoff (heavy rains leading to increase in surface runoff).

Climate change can also impact water demands and the reference (natural) conditions of water bodies.

• Water abstraction from rivers, lakes or groundwater that impacts on water stored and on

water flows with contiguous compartments. Agriculture, in particular when irrigated, also impacts evapotranspiration, interception and percolation.

• Flow regulation induced when building storage infrastructure for enhancing the reliability of

water supply or producing electricity can also influence runoff and infiltration or increase ground water recharge, depending on the size of the storage built.

• Land use change, including urbanisation, leads to soil sealing, increasing surface runoff and

decreasing infiltration and evapotranspiration, and affects groundwater recharge.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Environmental water requirements is a percentage of the available water required to be maintained for environmental purposes. It varies from 34% to 47%. It depends on the spatial scale of analysis and cannot be generalised for all rivers. Return water into the same hydrological unit where abstraction occurs. Depending on the water quality and location where the return occurs this returned water volume can be an

• important. Need to be accounted of a region or catchment to assess its current water stress

conditions.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Overland flow (surface runoff Rs) occurs when the rate of precipitation exceeds the interception requirements and infiltration capacity. The excess water accumulate in small surface depressions, and gradually forms an overland downslope flow. As rainfall continues, overland flow culminates downstream in the river through the main and secondary drainage network of the catchment, eventually contributing to the streamflow. Interflow (subsurface runoff (Rsub) is the portion of infiltrated rainfall that moves laterally through the upper soil layers until it reaches the stream channel. It depends

• n the physical characteristics of the catchments and the spatiotemporal

characteristics of the rainfall. Base flow (groundwater runoff (Rgw) is the portion of infiltrated rainfall that reaches the groundwater table and then discharges into streams. It responds much more slowly to rainfall and does not fluctuate rapidly. In areas with seasonal rainfall base flow gradually builds-up, peaking towards the end of the wet season. The overland flow together with the interflow are the two components of the Direct Runoff.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Desalination - specialised treatment method used to remove dissolved minerals and mineral salts mainly from sea water and convert it to fresh water for domestic, irrigation or industrial use. Principle risks and negative impacts are:

• Environmental risks –(i) aquifer contaminations (in the case that a desalination plant is constructed inland and

seawater has to be transported through pipes that can have leakages), (ii) marine ecosystem damage due to brine discharge to the sea, (iii) noise pollution and (iv) spoiling the coastal landscape, (v) potential accumulation

• f boron.
• Economical risks –high investment and recurrent costs, linked to energy requirements. Investments in an

added distribution network arise if the desalination plant is located far from urban areas and the existing main water supply.

• Social risks – concerns about the palatability of desalinated water and the effect on household goods are now

largely dispelled. The higher costs of desalted water will increase the global water price, which puts lower income households at risk.

• Global warming risks - Desalination is probably the option that has the highest green-house gas emissions

amounts per m3 of water produced. This is linked to the higher amounts of energy needed to desalt water (between 3.5 and 24 kWh/m3 according to the technology), especially with thermal processes.

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Wastewater re-use - is a valuable resource for water supply in areas where water is limited. Direct wastewater re-use is treated wastewater that is piped into a water supply system without first being incorporated in a natural stream or lake or in groundwater. Indirect wastewater re-use involves the mixing of reclaimed wastewater with another water supply source before re-use.

• It reduces the demands of freshwater, but can also reduce the pollution of rivers and ground

waters by nutrients (benefit)

• It requires strict quality controls needed in order to minimise the risk of environmental

contamination and human health problems (water-borne diseases and skin irritations) (risk). Rainwater harvesting - is the process of collecting, diverting and storing rainwater from an area (usually roofs or another surface catchment area) for direct or future use. This is a technology that can be used to supply water to households and industry.

• water quality is not adequate and therefore a risk to health
• financial resources to invest in this technology, and reap the benefits of lower water costs

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Groundwater recharge is a hydrologic process where water moves downward from the soil surface towards groundwater, both naturally (through the water cycle) and man-induced (i.e. artificial groundwater recharge). Artificial groundwater recharge aims at the increase of the groundwater potential by artificially inducing large quantities of surface water (from streams or reservoirs) to infiltrate the ground. It is commonly done at rates and in quantities many times in excess of natural recharge.

• reducing the threat of over-exploitation of existing aquifers, and decreases the risks of seawater

intrusion into aquifers at or near the coast (benefit)

• need to have strict quality controls to minimise the risk of environmental contamination and

human health problems (risk).

• there are no large storage structures needed to store water, structures required are mostly small

and cost-effective (benefit)

• an extensive and expensive tertiary treatment is required for using waste water to recharge

ground waters (although in most situations in the EU these are in place in any case) (risk).

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624 : Water Resources and River basin management

Issues in the integrated water management

Temporal scale Issue Indeterminate Flow necessary to protect endangered species Long-term Inter-basin allocation and allocation among basin states Decadal Upper basin delivery obligation Year Lake fill obligations to achieve equalisation with Lake storage Seasonal Peak heating and cooling months Daily to monthly Flood control operations Hourly Power Administration’s power generation Spatial scale Global Climate influences, Regional Prior appropriation State

Different agreements on water marketing for within and out-of-state water districts

Municipal and communities Watering schedules, treatment, domestic use

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 624: Water Resources and River basin management

River management needs observed / Monitor information on:

Meteorological – rainfall amount, variation, temperature (Min & Max) Humidity/aridity Run off – Surface run-off, silt/sediment content Storage facilities – conditions, release dependency –agriculture, drinking water, environment, industries Surface distribution system – conditions, missing connectivity, storage supplier status, water transportation probabilities Ground water availability – water table conditions, quality, movement Demand – supply situation – settlement, crop production, distribution constraints, fee collection Augmentation of facilities – possibilities financial EIA, socio-economic constraints, water sharing agreements, legal

• bligations/correction

Supplementary source - desalinization, rain water harvesting, conservation potential savings Scenario – water, livelihood, resources harvest, transporation, natural disaster, alternate source/distribution ways