Geotechnical Parameters Impact on Artificial Ground Water Recharging Technique for Urban Centers

Pratima Patel, Mahesh Desai, Jatin Desai
DOI: 10.4236/jwarp.2011.35035                

Abstract

Water scarcity is a serious problem throughout the world for both urban & rural community. Urban centers in India are facing an ironical situation of water scarcity today. This paper includes an Analytical solution, Numerical modeling, Empirical approaches, In-situ test results to predict recharge (rate) mound of the ground-water and capacity of recharge well which is essential for the proper management of suitable artificial ground-water recharge systems to maintain water balance and stop salt water intrusion. Authors have derived analytical equation for predicting growth as well as decline of the ground-water mound depending on the intensity of recharge rate qr with different value of permeability k, depth of pervious strata H and diameter of well d, also studying the effects of variation in the geotechnical parameters on water-table fluctuations. In this paper to study the impact of numerical modeling using quadratic equation for unconfined aquifer base on rainfall intensity P and a change in saturated thickness H with variation in piezometric level. Empirical approaches are for evaluation of correct value of k of an undercharged unconfined aquifer with drawdown s0, influence zone L, recharge rate qr. In-situ test results give actual correlation between value of recharging rate of well and permeability on field. Authors have verified recharging rate of installed well from all approaches. A result obtained from the various field case studies gives the validation of the derived equation. Scientific quality measures of aquifer water are also recorded.

Keywords

Unconfined Aquifer, Well Determinant – Recharge Rate & Hydraulic Conductivity, Geometrical Properties Of Aquifer, Pre Cast Octagonal Recharge Well

1. Introduction

Scarcity of water resources, pollution and climate change will be the major emerging issues in the next century. Due to depletion of water table, scanty and uneven pattern of rainfall, water scarcity is faced by arid and semi-arid district of Gujarat State. The runoff for roof top is computed based on average rainfall intensity. In addition to irregularity of rainfall, the change in life style, population explosion, rapid industrialization, rapid urbanization, irrigated agriculture and inefficient water management plan are the main factor which has lead to present water shortage problem. Recharge is a critical parameter for understanding, modeling and protecting groundwater systems from overexploitation and contamination. Adopting the concept of sustainability and conservation of water resources using artificial recharge technique can help to cope with the global water shortage.

Adequate space for surface storage is not available in urban areas, water levels are deep enough to accommodate additional rainwater to recharge the aquifers, rooftop and runoff rainwater harvesting (storm water reuse) is ideal solution to solve the water supply problems for better tomorrow. In this article simple methodology of recharging is highlighted. The collection of roof terrace water into detention tank and then recharges the unconfined aquifer through designed recharge well. Authors have derived general analytical equations for evaluation of recharging capacity of well with predominant geotechnical parameters like permeability of aquifer soil, depth of water table, depth of pervious strata, porosity and particle size of soil, etc. along this diameter of well, depth of well ,size of opening in casing pipe are also included. This derived analytical equation is verified by field test installing artificial recharge system at project site. Results obtained from all this approaches are confirmatory. Analysis of water quality and rise in water level in well done after one year which gives satisfactory working of the system.

2. Water Conserve or Fight War by 2050

Water is one of the renewable resources. About one-fifth of the world’s population lacks access to safe drinking water and with the present consumption patterns; two out of every three persons on the earth would live in water-stressed conditions by 2025. Around one-third of the world population now lives in countries with moderate to high water stress. India with an average rainfall of 1150mm is the second wettest country in the world with good water resources. But the water resources are not evenly distributed over the country due to varied hydro geological conditions and high variations in precipitation both in time and space. As a result, most parts of India experience lack of water even for domestic uses.

In Surat city (Gujarat State, India) source of River will give maximum 700 MLD. Then shortage of 150 - 200 MLD will be standing demand in 2050 as shown in Table 1.

3. Hypothesis of Water Available

Table 2 shows scenario of the costing of water available at present & in future. With the growing demand of water, ground water level dropped drastically, therefore artificial ground water recharging of aquifer by storm water reuse or surface water is the only answer for this water crisis. Thus, there is immediate need to conserve every source of usable water for the future generation. Planning and management of 10 years could post pone water crisis by few more years [1].

Conflicts of Interest

The authors declare no conflicts of interest.

References

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