Rain water harvesting is the way through which collection and storage of rain water that runs off from rooftop, parks, roads, open ground etc.
This runoff water can be either stored or recharged into the groundwater table.
The scarcity of water is increasing year by year in Pakistan. In past due to passing the Ravi River, the natural phenomenon at most of area of Punjabs water ground table recharging occurred. But now due to our negligence, ill government policies and political non-priority towards “Indus Basin Treaty”, set back the entire water source in the favour of India, who captured our all sources of water and is constructing water reservoirs year by year which is resulting in our water resources to decrease and making it difficult to carry on the natural phenomenon of water table recharging.
In next five years Pakistan will face lack of water at deadly level, so there is a need on emergency basis to develop management of water resource through rain water harvesting in urban areas especially the dense populated cities of our country.
Pakistan is the sixth largest country in the world with a population about 2.48 per cent of overall world population (UN, 2009). The total population increased from 34 million in 1951 to 170 million by the year 2010. In Pakistan the proportion of urban population increased 17 per cent to 36 per cent from 1951-2010 with urban population of 58 million and population of more than 209 person per sq km.
Both hasty urbanization and high population growth rate directly impacted the water demand for domestic industrial and agricultural sectors.
In Pakistan, about 96 per cent of its available water is being used for agricultural purposes 2 per cent for industries sector and remaining 2 per cent is for domestic uses.
In Pakistan at Punjab is much organized in water management aspects, beside that approximately 35 per cent of domestic water supply is unaccounted for water (UFW) because of management and material various issues and including rain water become sewer problem for urban management bodies especially during monsoon seasons many death occur and damage properties.
The availability of water from 1950-2010 is 5600m^3-1000m^3 which is itself a dramatic change due to our non-responsibility toward water resources saving, and put all responsibility on government and politician.
Some facts of water resources of Pakistan of water saving is we have
• Water surface about 138 MAF
• Total available storage 16MAF
• Sedimentation in storage – 0.16 MAF per annum
• Canal diversions – 106 MAF
• Groundwater availability – 55 MAF
• Groundwater withdrawal – 50 MAF
• Irrigated area – 18 Mha
• Available for additional cultivation – 12 Mha;
And water demand and consumption in Pakistan From 2004 up to 2025 will be
Due to unawareness about importance and need of rain water harvesting; we waste this natural and more beneficial for the health of human bodies and for local agricultural cultivation, and dump with waste polluted water it in our sewer by discarding it in.
These above some facts of lack of water availability and its consumption bomb in near future will explode in Pakistan and this start now; it only is stop by putting all resources and capabilities to manage water resources otherwise result in form of drought, etc.
On August 13, 2013, urban unit in Lahore at the Alhamra Art Council, arranged a seminar to grow initiative in favour of “Rainwater Management in Urban Areas”.
Earthquake Reconstruction and Rehabilitation Authority (ERRA), WASA, WAPDA and different other private/public sector departments and housing development organization represented were also trying to give boost to this concept during seminar in presentation.
Dr. Iftikhar Ahmad from College of Earth and Environmental Sciences, University of Punjab, Lahore, described the purposes, management condition of rainwater management in Punjab, benefits of use and recharge.
Syed Zaheer Hussain Gardezi; Project Director – PRWH Project, ERRA, also doing such a laudable work to reconstruction in northern areas which had got affected in the 2005 earthquake. Recently they applied the concept of Rain Water Harvesting (RWH) by “Roof top management technique” most of people of that area get fulfill their needs of water for domestic needs by snow falling and rain falling at the roof which accumulate at storage tank.
By Syed Muzammil Hussain Jafri Chief Engineer: In Gujranwala at DC Colony management has taken an initiative to accumulate the rainwater to recharge the Ground Water Table (GWT) of society by applying “PIT Technique” which grand total cost was more then 150,000/-Rs, and recharge the area of society GWT approximately >70,000>ft2.
methods for Rain Water Harvesting RWH;
• Roof Top Management. (Domestic/Commercial);
o Built In-situ storage Tank.*
o Ground Storage Tank.
• GWT Recharging.
o Recharge Pits.
o Recharge Well.
That has become the ground reality and need of the hour to implement the above-mentioned technique with proper codes; otherwise nature will not forgive us and take all the things which we take from it.
In Pakistan, there is an urgent need on an emergency basis to develop and implementation of water resource management in urban areas through RWH technique at dense populated city areas of Pakistan.
Both general techniques serve like which would I like to call “Bread and Butter Phenomenon; this is our daily life example at breakfast, when we spread butter on slice of bread, it fills up all pores of slice and remaining still on butter spreader.” So in the case of rain falling at city or some specific area same phenomenon will occur. If we build Rain Water Harvesting RWH techniques, and the remaining runoff on road or under local urban management areas which ease to control it so the chances of flooding will minimize less damages of local private/public properties, less consumption of manpower to control emergencies and minimize the chances of deaths.”
In rural areas of Pakistan the same concept of RWH technique was used, but not in an organized way. Due to this fact most of the storage water goes waste and polluted, not in used for domestic or agricultural purposes.
The government of Pakistan and provincial governments have to take initiatives in this aspect to make by-laws and codes by the help of technologists. To regularize that on residential, commercial, un-developed green areas, green belts between roads, parks and housing societies at urban areas.
Both the techniques of RWH has limitation in aspect of application;
The roof top management technique is only suitable at developed areas, while the GWT recharge technique is only suitable at large area where building are far to each other, due to this technique the chances of settlement of ground could be so the building collapsing chances increase.
So we have to understand the need of both techniques at suitable technique according to the principle of engineering.