Tuesday, 27 October 2015
Friday, 23 October 2015
Integrated Water Resource management
Water resources are sources of water that are useful or potentially useful to humans. Uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually all of these human uses require fresh water. 97.5% of water on the Earth is salt water, leaving only 2.5% as fresh water of which over two thirds is frozen in glaciers and polar ice caps. The remaining unfrozen fresh water is mainly found as groundwater, with only a small fraction present above ground or in the air. Fresh water is a renewable resource, yet the world's supply of clean, fresh water is steadily decreasing. Water demand already exceeds supply in many parts of the world, and as world population continues to rise at an unprecedented rate, many more areas are expected to experience this imbalance in the near future. This will lead a severe water crisis. The framework for allocating water resources to water users (where such a framework exists) is known as water rights.
Sources of Water:
- Surface water:
Surface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, and sub-surface seepage.
Although the only natural input to any surface water system is precipitation within its watershed, the total quantity of water in that system at any given time is also dependent on many other factors. These factors include storage capacity in lakes, wetlands and artificial reservoirs, the permeability of the soil beneath these storage bodies, the runoff characteristics of the land in the watershed, the timing of the precipitation and local evaporation rates. All of these factors also affect the proportions of water lost.
Human activities can have a large impact on these factors. Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans often increase runoff quantities and velocities by paving areas and channelizing stream flow.
The total quantity of water available at any given time is an important consideration. Some human water users have an intermittent need for water. For example, many farms require large quantities of water in the spring, and no water at all in the winter. To supply such a farm with water, a surface water system may require a large storage capacity to collect water throughout the year and release it in a short period of time. Other users have a continuous need for water, such as a power plant that requires water for cooling. To supply such a power plant with water, a surface water system only needs enough storage capacity to fill in when average stream flow is below the power plant's need.
Nevertheless, over the long term the average rate of precipitation within a watershed is the upper bound for average consumption of natural surface water from that watershed.
Natural surface water can be augmented by importing surface water from another watershed through a canal or pipeline. It can also be artificially augmented from any of the other sources listed here; however in practice the quantities are negligible. Humans can also cause surface water to be "lost" (i.e. become unusable) through pollution.
- Sub-surface water:
Sub-Surface water travel time Sub-surface water, or groundwater, is fresh water located in the pore space of soil and rocks. It is also water that is flowing within aquifers below the water table. Sometimes it is useful to make a distinction between sub-surface water that is closely associated with surface water and deep sub-surface water in an aquifer (sometimes called "fossil water").
Sub-surface water can be thought of in the same terms as surface water: inputs, outputs and storage. The critical difference is that due to its slow rate of turnover, sub-surface water storage is generally much larger compared to inputs than it is for surface water. This difference makes it easy for humans to use sub-surface water unsustainably for a long time without severe consequences. Nevertheless, over the long term the average rate of seepage above a sub-surface water source is the upper bound for average consumption of water from that source.
The natural input to sub-surface water is seepage from surface water. The natural outputs from sub-surface water are springs and seepage to the oceans.
If the surface water source is also subject to substantial evaporation, a sub-surface water source may become saline. This situation can occur naturally under endorheic bodies of water, or artificially under irrigated farmland. In coastal areas, human use of a sub-surface water source may cause the direction of seepage to ocean to reverse which can also cause soil salinization. Humans can also cause sub-surface water to be "lost" (i.e. become unusable) through pollution. Humans can increase the input to a sub-surface water source by building reservoirs or detention ponds.
Water in the ground is in sections called aquifers. Rain rolls down and comes into these. Normally an aquifer is near the equilibrium in its water content. The water content of an aquifer normally depends on the grain sizes. This means that the rate of extraction may be limited by poor permeability.
Water crisis: Water crisis is a term that refers to the status of the world’s water resources relative to human demand. The term has been applied to the worldwide water situation by the United Nations and other world organizations. The major aspects of the water crisis are overall scarcity of usable water and water pollution. 1.6 billion people have gained access to a safe water source since 1990. The proportion of people in developing countries with access to safe water is calculated to have improved from 30 percent in 1970 to 71 percent in 1990, 79 percent in 2000 and 84 percent in 2004, parallel with rising population. This trend is projected to continue.
The Earth has a finite supply of fresh water, stored in aquifers, surface waters and the atmosphere. Sometimes oceans are mistaken for available water, but the amount of energy needed to convert saline water to potable water is prohibitive today, explaining why only a very small fraction of the world's water supply derives from desalination.
There are several principal manifestations of the water crisis:
- Inadequate access to safe drinking water for about 1.1 billion people.
- Groundwater overdrafting leading to diminished agricultural yields.
- Overuse and pollution of water resources harming biodiversity.
- Regional conflicts over scarce water resources sometimes resulting in warfare.
Integrated water resource management:
Integrated Water Resources Management (IWRM)has been defined by the Technical Committee of the Global Water Partnership (GWP) as "a process which promotes the coordinated development and management of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems." Operationally, IWRM approaches involve applying knowledge from various disciplines as well as the insights from diverse stakeholders to devise and implement efficient, equitable and sustainable solutions to water and development problems. As such, IWRM is a comprehensive, participatory planning and implementation tool for managing and developing water resources in a way that balances social and economic needs, and that ensures the protection of ecosystems for future generations. Water’s many different uses—for agriculture, for healthy ecosystems, for people and livelihoods—demands coordinated action. An IWRM approach is an open, flexible process, bringing together decision-makers across the various sectors that impact water resources, and bringing all stakeholders to the table to set policy and make sound, balanced decisions in response to specific water challenges faced.
It has been agreed to consider water as an 'economic commodity' in order to emphasize on its scarcity in the Dublin Principles:
Fresh water is a finite and vulnerable resource, essential to sustain life, development and the environment.
Water development and management should be based on a participatory approach, involving users, planners and policy makers at all levels.
Why integrated water resource management:
- Global water: 97% seawater, 3% freshwater. Of the freshwater 87% not accessible,13% accessible (0.4% of total).
- Today more than 2 billion people are affected by water shortages in over 40 countries.
- 263 river basins are shared by two or more nations;
- 2 million tonnes per day of human waste are deposited in water courses
- Half the population of the developing world is exposed to polluted sources of water that increase disease incidence.
- 90% of natural disasters in the 1990s were water related.
- The increase in numbers of people from 6 billion to 9 billion will be the main driver of water resources management for the next 50 years.
Role of Remote sensing and GIS in integrated water management:
Water resources are the basis of sustainable development of society and economy. It is recognized from the present situation that the key issue is the management. If powerful engineering and non-engineering measures are adopted, the problem is really possible to be well solved. In fact, RS, GIS and GPS can play important role to water resources management, such as surface water, groundwater, snow and ice investigation, dynamic monitoring of ecology and estimation of water amount necessary for keeping and recovering ecological environment, existing irrigation area investigation and irrigation planning, soil moisture and drought monitoring, investigation of soil salinisation, planing, monitoring and effect evaluation of returning cultivated and to forest or grassland, dynamic monitoring of desertification and soil erosion, variation of river course and sedimentation in lakes and reservoirs, site selection of water project and its planning, design, construction and management.
1. Water resources investigation:
Discharge in river channel can be accurately controlled by hydrological measurement, while the area of reservoir and lake can be determined by remote sensing. On the basis of that, water storage in lake and reservoir may be determined. This can also be worked out on the basis of multi -temporal (flood, middle and dry periods) remote sensing images and corresponding simultaneous water levels in the lake or reservoir under investigation. This method is much economic than under-water topographic measurement. Key problem is obtaining enough multi-temple remote sensing images. Groundwater is the most important reproduced natural resources, especially for livehood, animal husbandry and agriculture in arid regions. Remote sensing can provides the information about geology, hydrogeology, geomorphology and urban environment analysis. They are helpful for searching groundwater, provides clue for field investigation and improve successful possibility. For finding groundwater, the penetration of radar is helpful to directly find shallow-layer groundwater in the places with ancient river channel and the plain area in front of mountains.
The major description of ice -and-snow water resources is the scale of glacier, extent, thickness
and properties of snow cover. Remote sensing has the ability for the observation in these aspects. With the advantage of high temporal resolution of meteorological satellites, it is possible to distinguish cloud and snow cover due to the movement of cloud. Moreover remote
sensing can play more rule to snow monitoring, such as the determination of the percentage of
liquid water in snow pack, so as to more accurately estimate the water equivalent of snow pack
and to perform snow-melting runoff forecasting.
2. Delineation soil moisture:
The dielectric characteristics of object are the principle factor deciding emissivity. The dielectric constant of water is 80, while dry soil is 3. The difference is very significant. It means that the dielectric constant is very sensitive to soil moisture content. It makes the change of soil emissivity from 0.95 when soil is dry to 0.6 or less when soil is humid, namely the variation of 30% on natural emissivity of soil. The main objective parameter affecting emissivity is the volumetric moisture content in soil layer from ground surface to the depth of 5 cm. This is just the theoretical basis for measuring soil moisture content by remote sensing. The soil property, surface roughness and characteristics of vegetal cover must be also considered.
The soil moisture content measured on ground is the major basis for calibrating the parameters
in drought monitoring model by remote sensing. After measurement, transmission and processing, soil moisture contents are input the GIS-based information management system. Two-directional inquiry can be realized, namely, to inquire soil moisture content from the location of sampling point and to inquire location from soil moisture content. Combining with multi-intermediary measures, warning will be issued by sound, color and light when soil moisture content decrease to a certain degree. Besides the depletion of soil moisture content can be predicted by hydrological model. With these information, and also the distribution of crops and water demand during corresponding growth period, decision for drought against measures can be made, namely, from where and when to divert how much water to mitigate the drought situation.
3. Dynamic monitoring of desertification and effect evaluation after harness:
Desertification is related to natural conditions, especially the vibration of climate and water resources, also related to excessive human -being activities. Desertification reduces farmland area, vegetation cover and grassland area, is also one of sources of desert storm and atmospheric pollution.
Due to the difference of climate and water resources conditions, there are three types of desertification, i .e. desertification of sandy grassland, activation of fixed dune and invading of moving dune. Facing the serious situation that desertification is still developing, the emphasis of harness will be laid in four regions.
For estimation of ecology water demand, it is important to combine remote sensing with conventional data, such as temperature, precipitation, runoff and topography. The basic idea is
(1) Ecological background is made first according to topographic and climatic (temperature and precipitation ) conditions.
(2) Ecological background is overlaid on land use classification from remote sensing to reflect the effect of non-climatic factors, such as runoff and human-being activities. The resulting in secondary sub-area involves controllable and non-controllable areas.
(3) On the basis of detailed classification of land use, third-class area is produced, ecological water demand can be estimated through quantitative calculation for each kind of unit area.
4) Irrigation area investigation and development planning
In order to contend water, irrigation area is blindly developed in many places. The irrigation area from statistics way is smaller than the actual one. It results in water shortage in downstream basin. In order to realize comprehensive management of water resources for the whole basin, the irrigation area is important and basic information.
4) Monitoring of salinisation.
Salinisation is a typical phenomenon of ecological environment in arid and semi-arid regions. It has direct interpretation identification in remote sensing images for bare land. The bare land includes the farmland after harvest or just after seeding, the farmland with poor plant due to salinisation. The most obvious interpretation identification for saline-alkali soil is the spot with light white color. The boundaries of spots are naturally curved. The shape of spot is belted, netted, annular, arched, divergent or mottled. In the infrared images during rainy season, the light color sources from the surface of saltern above the salinized soil layer, without or with less salt efflorescence. The surface soil becomes solid grey-white crust because the soil is lake of organic matter, impervious and poor aerated. It is different from the soil without salinisation or the salinized soil after flushing by rainfall, with relatively higher reflectivity. In dry season, the light color of salinized soil is caused by the salt crust or salt efflorescence formed due to salt movement to surface. With the increase of salinity, the reflectivity also increases gradually in the region of wavelength from visible band to near-infrared band, presenting a characteristic curve with near -yellow hue, because the white salt efflorescence has the yellow soil as its background.
Among the interpretation identifications of salined soil, hue is the most important one, but the shape identification in remote sensing image is also important. Such as the white spot on the both sides of ancient river channels are belted, those in river beach on low highland of sprindle,
those around depressions are annular, those on slope are of stretch and those in the boundary
of bursting fan are belted.
At present, remote sensing is very effective for monitoring blue green alga due to eutrophication in lakes and reservoirs and red tide along the coastal area. With the sampling on water surface, the water quality classification into five grades can be roughly done. In general it is carried out by the multi-band composition of ETM+ digital images. Which bands would be used are decided according to the major pollutants in the water body under investigation. The quantitative determination of various chemical elements by means of high spectrum is a forward research subject in the world.
5) Planning, construction and management of water project:
Apart from the consideration of hydrological factors and economic evaluation, the site selection of reservoir and key water control project must consider the topography and the geological evaluation which can be done by remote sensing and GIS. The planning of water diversion project can be performed on the digital platform. Remote sensing is the major source of data and information into GIS-based database, the spatial analysis and on-line virtual reality technology can play their important role on this basis.
6) Real-time monitoring and management system of water resources:
Due to the importance of water resources and extensity and complexity of its information, it is very necessary to establish a special system for real-time monitoring and information management to provide basis for decision-making on an integrating information platform.
The data of information sources from remote sensing and conventional measures are real-time data and historical data. Information is managed by GIS and can be used together through network System consists of four sub-systems, i.e. data acquisition, data transmission, data processing and decision-making support system (DSS). It can automatically acquires real-time data of hydrological data including rainfall, discharge and water elevation in river channel, lakes and reservoir, groundwater table, soil moisture content and so on, as well as water quality of surface water and groundwater.
In spatial database, there are real time data and historical data. The spatial data includes basic geographic data, such as water body, topography, land use, land cover, administrative boundary, communication, plant distribution, social -economic data, water resources data concerning utilization and development, such as water supply and demand.
Data processing includes the processing for remote sensing images and other data, also the update of database. In the respect of DDS, there are bank of models and expert knowledge; it can provide comprehensive and synthetic basis for decision making. The functions of the system are as follows.
Information inquiry can be carried out in two directions, namely to inquire attribute from location
on map and to inquire location from attribute or condition, rule and term.
The statistics can be done both in time and space or according to the condition, rule and term.
C) Prediction and warning
Combining with special models, what is made are water resources prediction, storm-flood
forecasting, low flow prediction, soil moisture content forecasting, snow-melt runoff forecasting
and prediction of water supply and demand.
D) Web GIS
Web GIS is adopted for this kind of system in order to realize operation and transfer in distance
and in multi terminals including the figures in sector format.
The planning includes water resources utilization and development, irrigation development,
water project, agriculture distribution, returning farmland to forest or grass and so on.
Consultation is often held for finding a solution concerning water resources management. This
system can no doubt provides information, alternatives and corresponding consequence for
7) Delineation of new catchment areas:
A catchment area is an extent of land where water from rain or snow melt drains downhill into a body of water, such as a river, lake, reservoir, estuary, wetland, sea or ocean. The drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels, and is separated from adjacent basins by a drainage divide.
The catchment 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 geographical barrier such as a ridge, hill or mountain, which is known as a water divide.
The below stated studies will be an important aspect for the study:
· Base map
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