METHOD OF PRESERVING AND HARVESTING RAIN WATER IN TRENCH LINED WITH PVC SHEET TO PREVENT FLOOD AND SOIL EROSION

The invention relates to "Method of preserving and harvesting rain water", more particularly the invention relates to solution to loss of rainwater due to evaporation & run off from top soil.

The existing technology for the preservation of rainwater & harvesting is as follows :

Rain water is stored in tanks and reservoirs and covered with a polythene sheet to avoid evaporation loss. Water holding capacity of these tanks is also limited and therefore 80% of rain water is being wasted.

Presently rainwater losses are as under :

Evaporation loss 35% and

Run off loss 55% thus.

Total 90% rain water is being wasted. This is a typical example given for the existing Rain water management.

Other existing method is farm-pond system. Here, also rain the water preservation is less than 10% of the rainfall in a farm. Depth of a farm-pond is 3 meter only water holding capacity of the farm-pond is approximately 10 lakh liters. Water is collected in the farm-pond during monsoon, for using this water in summer up to month of April/ May. But 2-3 meter stored water is lost due to

evaporation from the farm-pond and there is hardly any water in the farm-pond in summer. Therefore this technology is also not of much use.

The inventor with his research found a unique "Method of preserving and harvesting rain water " wherein 80% of rain water is recharged underground.

Presently in the agricultural land there is a 2' - 3' high soil bund boundry, which prevents rain water from going out of the farm. During rains some water is collected inside this boundary & excess rain water is lost as run off, which amounts to approx. 55%. Part of this collected rain water percolates underground up to a depth of 2' and remaining water is lost due to evaporation, which is approx. 35% rainfall. Therefore present use of rain water is 10% only.

Now the inventor with his innovative idea has made a Bandhara with PVC sheet by digging an underground trench inside the boundary of the farm, 2ft wide and 5 ft (minimum) - 10ft (maximum) depth, wherein the wall of this trench (nearer to the farm boundary and away from the slope) & bottom of the trench is covered with a 12ft wide PVC sheet and the trench is refilled with porous soil. The rain water collected inside the farm boundary percolates speedily underground through this trench (along the vertical PVC sheet up to a depth or 10ft), thereby avoiding run off loss of rain water as well as the evaporation loss. At the bottom of the trench water flow becomes horizontal (due to PVC sheet at the bottom ) & this percolated water spreads horizontally inside the ground, away from the trench in backward direction & water contents of the soil moves upward by capillary action & downward by gravitation, increasing ground water level substantially.

This trench (lined with PVC sheet & refilled with porous soil) acts as an artificial recharge path for rain water. When the quantity ^' of water in the soil increases

more than field capacity of the soil (say 20%), water starts flowing down towards the well & to deeper levels underground. In any case this soil water below field capacity is available to hair-roots of the trees & crops. As a result there is more than 75% saving in water & power for irrigation.

Main object of this innovation is to preserve & harvest more than 80% rainwater by making a trench underground inside the farm boundary and laying it with PVC sheet.

Another object of this innovation is to provide better water management for agricultural & drinking purpose throughout the year, saving water & power required for irrigation, & preventing soil erosion.

Further object of this innovation is to provide a low-cost rain water harvesting method even for individual farmer. This not only solves the ecological problems but also prevents the environment from further deterioration, by preventing floods.

Bandhara with PVC sheet is made by digging a trench of 2ft width X depth of 5ft (min.)-10ft (max.) just prior to the soil-bund boundary of the field in the farm and inside soil-check dam bandhara in a nullah and laying a 12ft wide vertical PVC sheet in this trench (2ft at the bottom plus 10ft on the wall away from the slope) & refilling the trench with excavated porous soil. For a bandhara in a nullah length of the trench should be same as width of the nullah. Length of trench for an underground farm bandhara can be approx. 100ft.

For in-situ rain water harvesting this is the best method because it creates a 'collecting zone', an 'artificial recharge zone' and 'no run off zone' in a farm or a nullah. This underground bandhara with PVC sheet is so simple and low-cost

that any individual farmer can make it in his field of 1 Hect. to 100 Hectares, within 3-4 weeks, under technical guidance.

Presently in existing ordinary bandhara (soil checkdam) water flow as run-off in the nullah from top 2ft surface of the ground. When reservoir gets full, water continuously overflows from the spillway of the bandhara because of slow underground percolation of stored water.

When a 5-10ft deep trench is dug & refilled with porous soil after placing a vertical PVC sheet, water does not flow in the nullah as run-off because of PVC sheet & water travels along this PVC sheet vertically downward up to the bottom of the trench where PVC sheet is laid horizontally & water starts flowing horizontally away from trench in backward direction.

Speed of water percolation is accelerated thro this artificial recharging path due to additional 10ft pressure-head created by trench depth. Within 2-3 weeks reservoir water percolates in the ground & bandhara is again empty to collect rain water. In one monsoon this farm bandhara (with trench & PVC sheet) can recharge water 4-5 times of the water holding capacity of the bandhara, earlier which was only 10% of the water holding capacity of existing ordinary bandhara.

Presently during monsoon farm becomes waterlogged near the boundary because rain water does not percolate 2ft below ground surface & evaporation rate is also very slow (3-5 mm per day). So normally a farmer cuts this soil bund boundary in the field and discharges collected rain water in neighbor's field. Fertile soil also flows out with this running water and there is very less moisture in soil immediately after monsoon.

Now a farm underground Bandhara with PVC sheet can be made prior to farm soil bund boundary (where min.soil depth is 5ft). From lHectare farm this underground bandhara can harvest more that 80% rain water (presently rain water harvested is less than 20%). Water logging does not occur in the fields because collected rain water percolates In the ground very fast (withing a day or two) & water does not flow out of the farm.

When water does not flow out of the farm, soil-conservation also takes place simultaneously.

Within 3-4 years of implementing this technique, soil moisture increases & even in non-irrigated land second crop can be taken after monsoon, without irrigation. This solves problem of drought as horticulture trees do not die during summer in drought period. This is a best solution to avoid floods in heavy rains. Increased moisture contents of the top layers of the soil attracts rain drops and water travels down in the ground to deep layers, and water level of the well increases during low-rains. Simultaneously fast percolation also helps in saving evaporation losses.

Accordingly the "Method of preserving and harvesting rain water "comprises of

1. A trench dug underground along & inside the farm (soil bund) boundary perpendicular to the ground slope, measuring 5ft-10ft depth X 2ft width.

2. Laying a 12ft wide PVC sheet in the trench 2ft at the bottom of trench plus 10ft vertically on the wall (near the boundary & away from slope).

3. Refilling the trench with porous soil, after placing the PVC sheet.

Method of preserving and harvesting rain water to prevent flood and soil erosion as claimed in claim 1 wherein making a trench under ground along the farm boundary (perpendicularly to the slop ) of the farm land measuring 5 to 10 feet in depth and 2 feet wide , placing PVC sheets along the trench wall (nearest to the boundary and away from the slop) and at the bottom (5) of the trench ; refilling the trench with porous soil (6) thereby 80% of the rain water is recharged under ground.

The invention will be described now with reference to Figure no. 1 & 2 in the accompanying drawing.

Figure 1 is the plan view of the trench provided in the farm.

Figure 2 is the cross-sectional view of the trench in the farmland. Referring to the figures 1 & 2 in the accompanying drawings.

A trench (1) is dug underground measuring 5 to 10 feet of depth and 2ft width near the boundary of the farm (2). A 12ft wide PVC sheet (3) is laid vertically on the wall of the trench near the farm boundary & away from the slope (4) and at the bottom (5) of the trench and refilling the trench with porous soil (6). The rain water will percolate underground at the boundary of the farm and go deeper up to 10 ft depth which will spread horizontally underground backward, away from the trench, thereby minimizing the evaporation losses & run off losses of rain water.

U.S.P. OF BANDHARA WITH PVC SHEET

1) Versatile : Useful for 1-100 acres farm

2) Simple : No engineer / contractor needed

3) Less time : 2-3 weeks by 2 couples

4) Individual : No need to make any group

5) Self-reliant No subsidy / loan required

6) Low-cost : Rs.3000+labour per structure

7) ^' Ample water : 20 lacs ltrs/acre water is harvested

( avg. rainfall - 630 mm)

8ϊ Power savine : >75%

"NO SUBSIDY NO LOAN, DO IT ON YOUR OWN, THEN ONLY WATER SCARCITY WILL BE GONE"

Permanent solution to water scarcity

1) Total FARM LAND RECHARGING by adopting innovative method. Only well recharging, farm pond, Vanrai Bandh or CCT may not solve the problem.

2) Recharging water underground should be more than extraction.

3) Proper planning for water use, based on recharging.

4) EVERYONE should harvest water individually.

FACTS

1) In last 50 years all water conservation projects have collected water ABOVE SURFACE.

2) More than 3mtr standing water is lost annually due to EVAPORATION from reservoirs.

3) More than 85% drinking & irrigation needs are fulfilled by EXTRACTING UNDERGROUND WATER

WATER USE

1) Irrigation : 82%

2) Industrial : 12%

3) Drinking : 6% and today we are facing DRINKING WATER SHORTAGE! !

TILL NOW

1) Rain water harvested : <20%

^• 2) Water wasted ^' : >80%

3) Only (+/-) 15% variation in average rainfall causes DROUGHT & FLOOD.

WHAT HAPPENS TO RAINWATER ?

As per Groundwater Survey & Dev. Authority (GSDA) of Maharashtra.

55% Rainwater is wasted as RUN OFF

35% Rainwater is wasted as EVAPORATION

10 % Rainwater is HARVESTED only.

Other data suggests we have been able to collect & harvest less than 18% RAINWATER.

This is an embodiment of the invention several modification are possible which may be considered within the ambit and spirit of this invention.