Morphometric study for water resource management using principal component analysis in Dhaka City, Bangladesh: a RS and GIS approach

Water resource management is essential to reduce the water scarcity and to meet demand for the over-growing population in the climate change world. The current study has focused on the water resource management using morphometric parameters (MPs) within the watershed around Dhaka City of Bangladesh. A casting model that includes principal component analysis (PCA), compound parameter (Cp) and priority ranking (Rp) was applied for the study by remote sensing and geographical information system techniques. According to the census of 2011, about 14.1 million population and 33.37 lac household exist in this city. To fulfill water demand, 2.0 Mm3 (78%) groundwater is extracted every day; therefore, groundwater level is declining day by day. To reduce the groundwater dependency, government has declared that the use of surface water will be increased to 70% (now 22%). For the current study, linear, aerial and shape MPs have been used on fourth-order (4 nos.), fifth-order (5 nos.) and sixth-order (2 nos.) watersheds to determine the water resource availability and conservation area. The linear (5 nos.) and areal (5 nos.) morphometric parameters have direct relationship to the soil erosivity and water conversion potentiality: increasing the grade of a parameter increases the potentiality; therefore, the final priority rank (Rp) has been taken 1 for the extreme grade of the parameters, then the next extreme grade has been taken as 2 and so on. The shape (4 nos.) parameters have inverse relationship to the soil erosivity and water conservation potentiality: increasing the grade of the parameters decreases the potentiality; therefore, the final priority rank (Rp) has been taken 1 for the inferior grade of the parameters, then the next inferior grade has been taken as 2 and so on. RL, Re, T and Lo are the effective parameters that have been obtained from PCA, and these parameters later have been applied for compound parameter (Cp) and final priority ranking (Rp) calculation. Final map shows that WS-7 (fifth order) has maximum priority (critical for water resource) and WS-8 (fifth order) has minimum priority (available water resource) for watershed management.