Centre of Excellence (CoE) for Integrated Landuse Planning and Water Resource Management (ILPWRM)
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Land cover changes can modify the natural hydrological cycle and thus the water resources are very sensitive towards the unplanned land conversions. Concrete built up areas are observed to have increased with urban expansion, which in turn have increased the surface runoff volume by reducing rain water infiltration and surface storage. Besides, unplanned land developments release more pollutants into the water bodies, both as point and non point source of pollution. The point source (industry, factory) impurity enters the water resource at an easily identifiable, distinct location through a direct route. On the other hand, non point source (NPS) pollution results from a wide variety of human activities on the land and thus comes from many diffuse sources. The natural pollutants and other human generated pollutants deposited on various land surfaces like roads, agricultural fields, construction sites, waste dumping sites etc are carried away by the rainfall moving over the ground and finally get deposited into surface water bodies.
Control of point sources pollution can be done by installing effluent treatments plants within the periphery of the source, however due to diverse origins; the non point sources are difficult to control than point sources. The control of non point source pollution can be achieved through a watershed based approach, taking into account the pollutant generation process by the various landuse activities and pollutant transportation by the surface runoff. 
For the conservation of water resources in urban watershed, watershed based landscape management approach can prove to be an efficient solution to control the increased surface runoff and non point pollution. The pollutant transport get substantially reduces in well manage landscape and therefore watershed management approach in developing urban areas can provide better opportunities to conserve water resources of the region. Also, proper planning and management of land uses enhance the ecological value of the landscape and improve their quality of services.

Ecological Management Practices

 Different structural and non structural measures are adopted to control storm water runoff and water pollution.  Structural measures deal with construction of structural arrangement (or structures) which provide an artificial way to capture and treat the wastewater or storm water. On the other hand, non structural measures deal with the sustainable modifications of the land cover which provide a natural way of controlling the quality and quantity of storm water.
Water pollution from non-point sources can be controlled to a great extent in a sustainable way through land management practices. Based on this idea, the concept of Ecological Management Practices (EMPs) has been developed, which can be defined as eco friendly sustainable management practices used for maintaining and enhancing land uses in a natural way. In other words, EMPs are basically sustainable measures that consist of combination of different structural and non structural land management practices adopted for controlling yield of pollutants from an area and transport of the same by the runoff.

Some for urban areas
So far, there is no well established EMP recognized as suitable for urban residential developments. However, various traditional land management practices are available to control the sediment yield and runoff volume for agricultural areas. Some of such practices are contour terracing, mulching, grass land development, creation of buffer zone with grass and tree, agro forestry, vegetated waterway and gully control measures. These practices, if suitably modified considering the necessity of an urban area, can also be used for land management of urban residential areas. Some of possible EMPs for urban residential areas are suggested below: 

  1. Grass land: Grass reduces the velocity of surface runoff, minimizes the impact of rain on soil and its root system helps in increasing infiltration. In urban area, grass land can also serve as open land that is needed according to the municipal rules.

  2. Forest land: Tree canopy reduce the direct impact of rain on soil. Besides, forest land, covered with falling leaves, also reduces the surface runoff velocity and increases infiltration. Falling leaves and decaying branches act as mulches and thus tree cover can control sediment yield and runoff volume.

  3. Covering rain impacted areas with pebble, vegetation or wood chips: Erosive power of rain drop depends on size of rain drop and its falling height. Size of rain drop that falls from inclined roof of a house become quite large and thus strikes the ground with very high erosive power. Thus, the portion of ground lying below the line of the roof edges is prone to more erosion as the accumulated rain over the roof falls with a high velocity. Such drop line areas of water around the house can be covered with pebble or wood chips or erosion resisting vegetation can be allowed to grow, which protect the soil from the direct impact of rain drop and also allow more infiltration.

  4. Detention drain and Retention pond:To capture the excess surface runoff, detention drains can be constructed across the slope and retention ponds can be constructed in a suitable location. This can minimize downstream erosion and flooding.

  5. Vegetated waterways:If the paths (or channels) of accumulated surface runoff are covered with vegetations, then the vegetation provide an obstruction to the flowing water. It reduces velocity and hence the erosive power of the flowing water. This reduces erosion of channel bed and bank and prevents gully formation. Root systems of a vegetated waterway not only increase bondage of soil and make it resistant to water erosion, but also promote infiltration. Depending on the status of degradation of the waterway, different types of vegetation can be suggested.

  6. Rainwater Harvesting System:Rainwater harvesting is a technique of collection and storageof rain water in surface (storage tanks) or sub surface aquifer before it is lost as surface runoff. Rainwater harvesting system helps in reducing the peak runoff and also recharges ground water. The collected rainwater through the rainwater harvesting system can also be used during the period of water shortage.

Concept of Optimal EMPs

EMPs differ in their implementation and maintenance cost from site to site and time to time. Scope of implementing an EMP in a particular site will have to be assessed by taking into consideration various site condition such as slope, soil characteristic, land ownership, land availability, present land cover and logistic of future maintenance. Besides, pollutant removal efficiencies of EMPs are also site-specific. Based on this, planning and design of EMPs should be done in such a way that they are efficient to capture and treat the pollutant loaded water and are ecologically and economically feasible.

An Optimization Model for selection of EMPs for developing a hilly watershed

Use of optimization technique in watershed level planning can provide an economic solution for selecting EMPs for a hilly watershed that can mitigate the soil erosion and flood hazard.  The EMP combinations should be such that it restricts sediment yield and peak flow to a desired level, minimizes in total cost for the whole watershed, and also satisfies the other logistic need of the watershed