Articles

  • RAINWATER HARVESTING CRITICAL EVALUATION by AdministratorPosted on : 10 December 2010
    • Abstract
      Obstructing and enhancing the natural process is considered as base of growth and development e.g. the dam stores the rain water by obstructing the natural river flow. Further diverting or lifting the stored water through pumps enhances the process of irrigation it has shown miraculous rise in the agricultural growth. However over a period of time the negative & adverse impacts of these activities are being observed. The environment gets deteriorated and sometime the condition become alarming by rise in the salinity of soil. Green bonds by growing the manmade forest in 80’s was consider as the economical boom, is now almost forgotten. Many people lost their hard earned money in Green bond because  manmade forest could not grow Hence critically evolution of any manmade accelerated process is must.
      Surface water and underground water are naturally replenished & recharged with rainwater. Lakes and dams are well known for arresting and store the rainwater by manmade efforts. However it cannot satisfy demands of growing urbanization and industrialization. There are, and will be continuous efforts to find out alternative methods to satisfy water demand. From 1990 onwards rainwater harvesting is becoming more popular. It is considered as simplest, economical to store and recharge underground water. No doubt that rainwater harvesting is proved successful at many places. Because of varying geographical & geological conditions rainwater harvesting cannot be considered as the only & best solution to be implemented at all the places. There are the disadvantages of rainwater harvesting which are not yet seriously studied. Some of key factors to be evaluated are as follows,
      a)    Characteristics ofrainwater
      b)    Composition of soil and rocks
      c)    Physical and chemical interaction between rain water and underground soil strata
      d)    Permeability and water percolation of soil
      Rainwater is without dissolved solids. Its Langlier index is negative and is highly corrosive. If rainwater comes in direct contact with underground soil strata then leaching of chemicals from soil & rocks cannot be ruled out. 
      The rules and regulation framed by central, state and local authority is binding the people to execute rain water harvesting. It is mockery of planning, that first natural percolation of water is discontinued by constructing the concrete structure and then compelling to enhance the percolation rate of rain water through remaining small open area by rain water harvesting. Therefore Author has recommended that the direct or enhanced recharging of ground water is to be critically evaluated along with likely side effects of change in underground water quality. An integrated approach is must to implement rainwater.