Development of drainage plan for waterlogged areas of Darbhanga district using remote sensing and GIS approach
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Date
2020
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DRPCAU, Pusa
Abstract
In India, rainfall is variable which causes flood and drought frequently. In Bihar, out of 38 districts, 28 districts will become flooded and 15 districts among them will get extremely affected in every consecutive year. Nearly, 73.63% of the geographical area of North Bihar is considered to be prone to floods. Next to flood, congestion in drainage of surface water resulting into water-logging is another major serious problem in the Bihar state. The combined use of remotely-sensed images and GIS based environmental applications in this work is needed for systematic ideas and scientific planning in the Darbhanga district of Bihar. Image processing and water-logged area assessment was done using ArcGIS and eCognition software.
The index-based classification method was followed in an ArcGIS software and as a result, various indices such as NDVI, NDWI, MNDWI (Esri), MNDWI (IHS) had been obtained to assess the water-logged portions. Among the various indices used in different months False Colour Composite image, it was found that the month of September (2017) is the best month to indicate, assess and delineate the water-logged areas. Comparison with the other indices, MNDWI was highlighting the water-logged portions in the better way. The object-based classification was carried out in eCognition software which will convert the pixels into objects. The water-logged boundary layer was extracted by using the threshold value of -0.175 in the September month MNDWI raster. The total area
subjected to water-logging in the Darbhanga district was found to be 42,282 ha. The area of water-logging was found in the two sub-divisions of the Darbhanga district. The blocks of Darbhanga and Biraul sub-division, holding the water-logging area of 21,899 ha and 20,383 ha respectively.
The maximum expected rainfall at 60 per cent, 70 per cent and 80 per cent probability levels were found using Weibull’s formula and 70 percent maximum rainfall of consecutive days was considered for the drainage characteristics which have been analysed with the formula of volume-balance method. The average pan evaporation loss was estimated as 0.385 cm per day. The average percolation loss was found based on the previous research works and considered for analysis of drainage characteristics. The drainage coefficient of consecutive days i.e., 1-,2-,3-,4-,5-,6- and 7- days for the blocks of Darbhanga sub-division was found to be 27.71, 16.93, 12.57, 10.42, 9.19, 8.35 and 1.60 cm per day respectively and for the blocks of Biraul sub-division it was computed as 18.12, 10.94, 8.07, 6.66, 5.85, 5.31 and 4.79 cm per day respectively.
The surface drainage plan for the blocks of Darbhanga and Biraul sub-divisions have been expressed by showing the main drain lines and outlets which was based on the comparison of different thematic maps. The useful measures also have been suggested to execute the drainage plan in an active manner.