Agro-Forestry: Controlling Flood Waters to Conserve Groundwater Reservoirs

Pakistan once had visible forests from our far north all the way to our seas in the south. In my youth (1950s-70s), Pakistan was immensely green, however, as I grew up I witnessed that over the decades we have destroyed our “Green Gold” in the name of industry, greed and incompetence. Today Pakistan has forests covering less than 2% of its total land mass, the majority of these forests exist in only the north of our country – Khyber Pakhtunkhwa and Gilgit-Baltistan. This figure ideally should be at over 30% to help not just economic growth but to stave off the deadly effects of global climate change. Experts have stated that Pakistan may not have any forests in the next 50 years if we don’t act now. Thankfully, we are starting to have a great deal of public awareness regarding this dire situation. Pakistan has started forestation programmes such as the Billion Tree Tsunami, Green Pakistan Programme, South Punjab Forest Programme and United Nations efforts under REDD+. 


Trees absorb water from the ground, approximately 750-1,500 litres a day and release it into the atmosphere in a process known as transpiration. A tree has the capacity to use groundwater deep under the ground as far as 30 metres, in limited quantities. The approximate litres of water a tree requires per day on average per year can be calculated by: 
Number of litres (per day)=Water required/years x25 number of trees/hectare


To achieve effective control of groundwater recharge per hectare we must plant a minimum of 600 trees in 3x3 metre spacing to help trees take on 15 litres of water per day from the soil to allow for transpiration of 500 ml per year. We need to study soil composition and permeability when planting our trees to better understand how we can aid this process. The pattern of soil structure must also be studied in high flood risk areas. Some major types of soil and their water penetration is:

Agro-forests must be developed in both rural and urban areas to maintain water cycle balance. We should begin a concentrated afforestation programme. This will help strengthen river banks and reduce the effects of flooding in addition to encouraging the absorption of water.


There is a need to employ thousands of our youth during their summer vacations to help create small ponds and lakes in low lying areas covered with trees. These water sources can also be used to meet drinking water needs of domestic animals. Ponds and lakes should cater to allow no less than 1,000 cubic metres of water storage. These animals which provide our dairy and meat can be helped greatly by such small measures. Such small ponds and lakes help in maintaining water reservoir on the surface and the ground penetration helps to fill our acquifers. 


The Government (Federal and Provincial) should direct relevant departments (for example, Survey of Pakistan, etc.) to carry out field surveys and mark all types of geographical depressions in flood prone areas and to further conduct soil tests to check on water permeability as well as financial studies to convert such areas into local ponds or lakes and further planting of trees surrounding these newly created ponds and lakes should take place. While doing so, taking into consideration that species of trees planted should not be water greedy, such as Azadirachta Indica (Neem Tree).


With proper management, flood waters can be diverted into artificially created ponds and lakes with the suitable soil texture to allow deep penetration into the soil. The use of bio-pores become very effective in soils with texture of clay, silt clay and clay loam. Bio-pores can be constructed from cement or PVC, with sizing at 10x100, 15x150 or 20x200 centimetres. The land which remains uncultivated can be prepared to receive flood waters by constructing high bunds around the land and placing sufficient bio-pores to allow quick water penetration into the soil. This will help the land deposit incoming silt which accompanies flood waters. 


Agro-forests must be developed in both rural and urban areas to maintain water cycle balance. We should begin a concentrated afforestation programme. This will help strengthen river banks and reduce the effects of flooding in addition to encouraging the absorption of water. Trees which are proven to help with the absorption of rainwater include the Ficus Benghalensis (Banyan Tree), Ficus Religiosa (Peepal), Syzygium Cumini (Jamun Tree), and Thespesia Populnea (Indian Tulip Tree)

Building dams is a long term process which takes an average of ten years to complete. With construction initiated in 2011, Diamer Basha Dam might be completed in 2022. In these ten years if all the Provincial Governments had employed people to help with forestation along the major rivers, low lying hills; agro-forests in cultivated areas could have had helped save immense amount of fresh water from being wasted. 


In urban areas, parks should have deep ponds with fencing to prevent children from falling into the water. Urban forestation should concentrate on planting trees which are large and shady and do not soak up excessive amounts of groundwater, a good example would be the Azadirachta Indica (Neem Tree). During heavy rains these ponds will facilitate penetration of water into the soil depending on soil texture and use of bio-pores. Bio-pores are being used worldwide in urban areas, such as Indonesia, Netherlands, Malaysia, Japan, Russia and United States, etc. With fresh water being a finite resource, we need to ensure maximum water retention to increase our groundwater and aquifers. 
In rural areas, space between two hectares of unused land or crop fields, or more can have a border of trees which can help in deep penetration of rain and flood waters. The space between different crop fields or land filled with trees in single, double or triple rows in spacing of 12x12 or 15x15 metres depending on the tree type. Benefits would include cleaner water, air, food quality and increase in local wildlife. 


Let’s first take a look at the Eucalyptus trees and why they were planted in such massive numbers in Islamabad. Did we expect our Capital to turn into a huge water logged or swampy area like Jakarta or turn into the Venice of the subcontinent? “Make the Capital Green” was the slogan of Capital Development Authority (CDA), so the administration had to find fast growing trees. Considering the damage Eucalyptus has done to the groundwater reservoirs or the Paper Mulberry trees which release and saturate the air we breathe with allergens, we must now move forward on a wave of change and plant ecologically compatible trees in Islamabad. 


Perhaps some PhD professors can help the CDA understand that they must remove the masses of Eucalyptus trees planted in F-9 Fatima Jinnah Park and replace them with trees which are more suited for our area such as Chir Pine, Neem, Banyan, Jaman, Ashoka, Sohanjna, etc. If we must plant “exotic” trees why not choose something edible such as Olive? These trees should not only be restricted to our parks, but must be planted throughout the city. We must increase our canopy! Variety of trees local to our country include:


Our real estate tycoons destroy the sources of rain water penetration by paving over natural green areas without any environmental planning. One inch of rainfall over 0.50 hectares of paved area/parking lots leads to the loss of approximately 1 million litres of potential groundwater. If bio-pores are constructed between each tree or bush planted in the greenbelts along the paved areas/parking lots or roadways, it will not only prevent water from damaging roadways/paved areas but will allow for water to more easily drain into deep soil, helping to increase our groundwater.


In addition to planting trees, another helpful step would be to utilise the many dry dug wells in various parts of the country. These wells, often left untouched after their water has gone dry, can be essential in helping rejuvenate groundwater. If these wells are in areas which are prone to flooding, such water may be diverted into these wells where their depth and storage capacity will help to allow seepage of the water into our natural aquifers. 


Building dams is a long term process which takes an average of ten years to complete. With construction initiated in 2011, Diamer-Bhasha Dam might be completed in 2022. In these ten years if all the Provincial Governments had employed people to help with forestation along the major rivers, low lying hills; agro-forests in cultivated areas could have had helped save immense amount of fresh water from being wasted. 


While we have started to take action and forestation programmes are underway, we must ensure as a nation, that we take issues of environment and climate change as a national priority and attach to them the same importance as our national defence. We must stay the course for our future generations, so that they too can have forests which we have.


The writer is member of the Advisory Board at the Center for Global and Strategic Studies (CGSS). 
E-mail: [email protected]

Comments



Note: No comments!


Leave a Reply

Success/Error Message Goes Here
Note: Please login your account and then leave comment!
TOP