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Appropriate water resources management to mitigate impacts of drought and floods
2008-01-23 08:39:03
By Deodatus Mfugale
The storm came without warning and, with it, a torrential downpour that pounded the city of Mwanza for just about 30 minutes.
Yet it caused flash floods that swept down several houses and other property leaving a number of families homeless.
And by the time all was over and as residents were taking stock of their losses, murky pools of water had formed on streets and on some courtyards.
The runoff had taken with it sewage from overflowing latrines and deposited it at some points on its way to Lake Victoria.
It was not an extraordinary event. It has been happening almost every year since 2000 and the floods in 2006 were very devastating.
People are now getting used to it although measures are being taken to mitigate the impacts.
As always, the Bugando section of the city was hard hit.
The houses in the area which are built on slopes are constructed with no discernible plan.
Residents have also cut down many trees to provide for new settlements.
The event this time around was a painful reminder to Mwanza residence of the storm in 2000 which came as suddenly and had equally devastating effects.
Several houses were pulled down; property washed away, sewerage from overflowing latrines spread onto compounds and into Mirongo River which pours its contents into Lake Victoria.
An impending outbreak of waterborne diseases usually hangs in the air like a soldier's sword on a helpless enemy.
The intensity and frequency of the storms is alarming but experts have attributed it to climate change which is also evidenced by unpredictable weather, unusually short or long seasons and extreme temperatures.
This means that while one part of the country may experience heavy rains, another part may experience severe drought and whereas one part my experience extremely low temperatures another part may be experiencing heat waves.
``Specific hazards of climate change are becoming more frequent. The most common are floods, droughts and storms,`` says Prof Paul Desanker of Penn Stare University in one of his presentations on Climate Change.
He explains that the Intergovernmental Panel on Climate Change (IPCC) predicts that these will get worse.
Given this situation, measures to mitigate the effects may also vary from place to place, depending on specific effects of climate change those parts are experiencing.
Bugando area of Mwanza city has been facing devastating effects of flash floods mainly for two reasons.
One is that many people have built their houses on hills and slopes in the course of which they cut trees, and destroyed natural vegetation.
As a result when it rains the effect of runoff is huge since there is nothing to retard the speed of water running downhill.
The storm water fills in latrines and cesspits and the strong runoff thus washes it away, to deposit it in rivers and into Lake Victoria, thereby polluting it.
The other reason is the poor layout of houses that have been built on the slopes.
Due to lack of planning, these structures have been constructed in such a way that they block the free flow of water down stream.
In principle, water will always find its own level and pull down or circumvent any obstacle in the course of doing so.
Most of the houses built on the slopes cannot withstand the pressure of the water and are thus pulled down.
There is also no proper drainage system, including open storm drains, which would direct the water down the slopes and into designated areas of discharge.
Likewise the area lacks proper sewerage and sanitation facilities with the result that pit latrines become full and easily overflow during the rainy season.
Speaking at the Second Basin wide Stakeholder Consultative Conference for the Zambezi Basin in Windhoek, Namibia, Principal Secretary in the Ministry of Irrigation and Water Development in Malawi, G. Malunga, said that taking an integrated approach to developing and managing water resources can more effectively tackle specific water challenges such as controlling flooding, mitigating the effects of drought, and eliminating water-borne diseases.
It implies that in order to mitigate the effects of the Mwanza flash floods, for example, residents should embark on proper planning of settlements on the slopes and hilltops.
Moreover, settlements should be built in a discernible order providing room for the construction of drainage systems including storm drains so that water is directed through a defined ``route`` down the slopes and thus save houses from being washed away.
It is all within the concept of managing water and land related resources to improve the social welfare of the residents and at the same time sustain the ecosystem.
Environmental engineers advise that construction of proper sewerage and sanitation system would reduce incidences of waterborne diseases and promote the health of the residents.
Another element in the intergrated approach would be to start a tree planting campaign which would not only stabilize the soil on the slopes but also help to check the impact of runoff as they would act as deterrents and slow down the speed of the water.
Unplanned and extensive construction has loosened the soil resulting in occasional land slides.
The trees will also reduce the impacts of storms as they would act as wind breakers.
Integrated Water Resources Management (IWRM) can invariably reduce the impacts of climate change particularly in areas where there is too much rain and in those where there is too little.
The IWRM process seeks to institute a coordinated development and management of water, land and related resources for, among other things, an improved welfare of the community, without impacting negatively on the sustainability of the ecosystem.
Moshi Municipality in Kilimanjaro Region is also located on a hilly terrain but due to proper planning of settlements including the provision of elaborate drainage and sanitation systems, residents do not experience impacts similar to those felt by their counterparts in Mwanza.
Moreover, Moshi Municipality as well as adjacent townships like Marangu is all covered by trees, a situation which prevents soil erosion, flash floods and land slides.
On the other hand, Isimani Ward of Iringa Region is experiencing a situation different from that of Mwanza city.
The ward which used to be among the major producers of maize in the country can now hardly produce enough for its people as it has been facing unusually long periods of severe drought due to climate change.
The condition has put stress on the water resources and residents of the area now face acute shortage of water.
The rainy season is unusually short and the rainfall intensity has been reduced drastically. Almost all the rivers in the area have now turned seasonal.
``The situation has its background on bad farming methods that have been employed over the years but I think climate change has compounded the problem,`` explained Gabriel Fuime, then Iringa District Executive Director, adding that farmers cut down forests to expand farmland, ``chasing`` away the rain in the process.
The intensive use of chemical fertilizers has also made the soil lose its fertility in the long run.
Reforestation campaigns have now started in an effort to retain soil moisture and lure back the rains.
Experts have recommended that as a quick fix, people should plant deciduous trees to mitigate the problem of water scarcity.
These consume less water during critical periods of shortage and compete less with crops.
They shed their leaves between one to six months per year and are suitable for semi-arid areas.
In the meantime, rainwater harvesting is being encouraged with some villages making large pans to capture rain water.
However, such water is mainly being used for agricultural purposes.
Due to the absence of natural vegetation and soil cover, the water has attained the red colour of the soil, making it unfit for both cooking and drinking. A few people use it for their livestock.
The residents could also engage in organic farming as a way of reviving soil fertility and retaining moisture.
This would involve training small scale farmers in the use of manure instead of chemical fertilizers and pesticides so that they may revive soil fertility.
The farmers would also be trained in soil conservation and environmental restoration in order to restore their neglected fields.
``Through improved soil management, crop diversification and natural pest control, small scale farmers can not only improve soil fertility and moisture, but they can also enhance their food security and raise incomes,`` says Mihayo Matinde, Tanzanian staff member of Export Promotion of Organic Products from Africa (EPOPA), in one of their recent publications.
He adds that organic farming projects have changed lives of small scale farmers in Mara region of North Western Tanzania by improving soil fertility and raising crop yields.
What is clear here is that as the effects of climate change continue to bite, communities have to employ appropriate IWRM approaches in order to mitigate the effects.
This feature has been produced with support from SADC/DANIDA and SARDC.
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