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译:Harnessing the rain

来源: 时间:2011-5-19 9:03:00 点击:

Water harvesting really works and governments in sub-Saharan Africa have a key role to play in promoting it, writes Maimbo Malesu. Chiefly, they can provide financial incentives and grants for rural and urban projects.


There is an overdependence on rain-fed agriculture in sub-Saharan Africa and not enough ways to deal with the effects of dry spells and droughts. As a result, grain yields are below one tonne per hectare in most of the region. This has mistakenly been blamed on physical water scarcity. But it is not physical as much as it is economic. There is simply a lack of investments to both capture and boost water storage.

Most sub-Saharan African countries are currently using at most 5% of their rainwater potential. By recognising and incorporating the greenwater — the water ignored in hydrological planning — it may be possible to improve the food insecurity situation while also protecting the environment.

To help alleviate hunger and poverty, the Swedish International Development Cooperation Agency (SIDA), through its Regional Soil Conservation Unit, helped establish the Southern and Eastern Africa Rainwater Network (SearNet) in 1998. SearNet consists of 12 national rainwater associations that work together to publicise rainwater harvesting information and innovations throughout the region. The network is hosted by the World Agroforestry Centre in Nairobi.

In collaboration with Rwanda’s ministry of agriculture and animal resources, the World Agroforestry Centre pioneered a method for upscaling trapezoidal-shaped ponds with off-stream runoff water conveyance mechanisms that facilitate the supply of water for irrigation and livestock development. The ponds can hold 120 cubic metres of water and are lined with a 0.8-millimeter plastic sheet. Inexpensive materials, including rope, a washer pump and a siphon or easy-to-use treadle pump are used to bring the water up from the pond.

As the pond costs around US$800, farmers would need a subsidy, a cost-sharing facility, or microfinancing to afford one. But the payoffs can be huge. Cost-benefit studies indicate that, with good management, farmers recover their investment costs in just two or three years.

With access to more water, farmers are encouraged to plant vegetables such as kale, tomatoes and onions as well as fruit trees, including mangoes and pawpaws [papayas], to boost production and improve nutrition. This innovation has spread across 10 districts in Rwanda: more than 400 ponds have been constructed and 800 more are in the pipeline.

Rural women spend at least three to four hours a day collecting water from distant and often contaminated water sources for use in cooking. This is especially burdensome for girls who are in school; they have to wake up early in the morning, haul water and then rush off to class.

In the Kajiado District of Kenya, the UN Environment Programme (UNEP) and the World Agroforestry Centre have worked with Maasai women to build roof catchment ferro-cement tanks to provide domestic water for their households. Members of women’s groups were encouraged to donate some of their own money so they could get matching funds from UNEP and the centre. The women also provided local materials such as water, sand and stones as well as labour for construction of the tanks.

After initial training, 86 tanks were constructed. In addition, the women were encouraged to plant 100 trees for each tank built. The project is being upscaled on a rotational basis, with a target of each woman eventually having her own tank. Rotary International of Canada then adopted this community, and more than 200 tanks have been constructed using the same model. This has improved health, and the women have more time for other fund-raising activities.

Farmers do not need expensive gadgets to find groundwater to help irrigate their crops. Green twigs, copper wires and plumb bobs can be used to locate and determine the width and status of underground water bodies. Green twigs from Croton megalocarpus or C. microstachys tree species found in semi-arid lands have been known to perform better than those from other tree species. The copper wire is used to determine the width of an underground water body, while the plumb helps estimate the depth.

All in all, these tools have been used to map underground water bodies. A comparison with terrameters, the devices used by civil engineers in groundwater prospecting, has confirmed that these other tools are not only cheap (or free, for the twigs), but also accurate.

In the western and Rift Valley regions of Kenya, water can be the entry point to rural development. Harnessing rain through water harvesting and conservation agriculture methods such as no-till farming and cover crops provides the basis for productive ventures that are crucial in helping to increase food self-sufficiency and improve rural economies. For annual crops, changes in yield are immediate. For perennial crops, it takes a few years before the impacts are realised. But with good agricultural husbandry, it is possible to realise positive returns when the availability of water or moisture is integrated with soil fertility management.

Water harvesting is more than just a matter of constructing ponds, dams, wells or tanks, of course. It is a slow process of creating, of organising communities to develop, maintain and manage water-harvesting activities, of involving communities closely in every aspect of the project, and of setting up systems for using and sharing water sustainably and equitably. This is also precisely the reason why it has to be a matter of community involvement and participation.

It is crucial, therefore, to create awareness and confidence among farmers and communities that water harvesting really works. The government should be a facilitator rather than an implementer. It has an important role to play in catalysing the widespread practice of water harvesting. And the government could get scientific organisations to develop better designs of the systems. But the most important role for government is to provide financial incentives and grants for water harvesting in rural and urban areas.


(译文如有出入请联系本会,来源于chinadialogue)

译   文:

善用雨水

  曼波•马勒苏认为,水资源的储集能够有效解决撒哈拉沙漠以南地区非洲国家所面临的水资源短缺的问题,而该地区的各国政府应在推广这一技术的过程挥重要作用。最主要的是,他们应该从财政上为城乡地区开展这一项目提供奖励和资助。


  撒哈拉沙漠以南的非洲地区的农业过于依赖雨水的浇灌,缺乏应对干旱影响的有效措施。因此,大多数地区的农作物产量每公顷还不足一吨。人们错误地认为导致这种状况的原因是水资源的稀缺,其实,与其说是水资源短缺,还不如说是经济匮乏。就是在关注和推动水资源储集方面缺少资金投入。

  目前,大多数撒哈拉沙漠以南非洲国家的雨水资源利用率最多只达到5%。在水文规划中,绿水海域是一个被人们忽略的领域。然而,如果我们能够认识到它的价值,并将其纳入到规划中来,那么就不仅有可能改变粮食危机的状况,还能够同时保护环境。

  为了帮助这些地区缓解饥饿和贫困的状况,1998年,瑞典国际合作开发署(SIDA)地区土壤保护机构协助建立了南部非洲和东部非洲雨水网络系统(SearNet)。SearNet成员包括12个国家级雨水利用联盟组织。这些组织共同合作,面向整个地区进行雨水收集信息及创新举措的推广。该联盟由总部设在内罗毕的世界农林研究中心主持。

  通过与卢旺达农业及动物资源部合作,世界农林研究中心另辟蹊径,推广一种配有径流输水系统的梯形蓄水池来为农作物及牲畜养殖提供水源。蓄水池的储水量可达120立方米,内部覆盖着0.8毫米厚的塑料薄膜。此外,为了将水从水窖中抽取出来还用到了绳子、洗涤泵、虹吸管或易用踏板抽水机等成本不高的材料和设备。

  每个蓄水池的造价约为800美元。因此为了能够让农民们建得起水窖就必须通过补贴、成本分摊、或者是小额贷款等手段向他们提供资助。然而,这些投入的收益却是相当可观。成本-收益分析显示,如果管理得当的话,只需两到三年,农民就能够收回投资成本。
有了更多的水资源,农民们不仅可以种植芥蓝、西红柿、洋葱等蔬菜,还可以种植芒果和木瓜等果树。这样一来,不仅能够提高农作物产量,人民的营养状况也得到了改善。这一技术已经在卢旺达的10个地区得到推广,共修建了400多个蓄水池,另外还有800多个正在计划之中。

  农村的妇女们每天至少要花费三到四个小时从很远的地方挑水,即便是用来做饭的水也常常是取自那些污浊的水源。这对那些还在上学的女孩子们而言则更是一项非常繁重的任务。她们每天必须很早就起床挑水, 然后再匆匆忙忙地跑去上学。

  联合国环境规划署(UNEP)与世界农林研究中心共同合作,在肯尼亚的喀贾多地区帮助马赛族妇女修建屋顶钢筋混凝土蓄水箱,从而解决了她们家庭用水的难题。UNEP和中心还鼓励妇女组织的成员们拿出一部分自己的钱,这样她们就可以获得对等的资金支持。此外,在蓄水箱的修建过程中,这些妇女们不仅提供了诸如水、沙子、石料等当地的材料,还付出了艰辛的劳动。

  在经过一些初期的培训后,一共修建了86座蓄水箱。不仅如此,还鼓励妇女们每修建一个蓄水箱就种植100棵树。该项目还在轮流的基础上逐渐扩大规模,其目标就是最终使每个妇女都能够拥有自己的水箱。随后,这个部落由加拿大的扶轮国际组织接手扶植,并沿用同一模式建设了200多座水箱。这一举措不仅改善了人们的健康状况,还让妇女们有更多的时间从事其它能够赚钱的工作。

  农民们不需要借助昂贵的设备就能够找到地下水源来灌溉他们的作物。他们只需借助绿色的枝蔓、铜丝、以及吊线锤这些就能够找到并且探明地下水系的宽度和状态。与其它树种相比,大果巴豆或细穗香茅科的树木在半干旱地区的长势更好。铜丝用来测定地下水体的宽度,吊线锤则是用来估算其深度。

  总而言之,人们一直使用这些工具来探测地下水源。与地下探测仪、以及土木工程师所使用的地下水探测装置相比,可以肯定地说,这些工具不仅便宜(甚至不花一文,比如绿枝),而且精确。

  水资源可以作为肯尼亚西部及东非大裂谷地区农村发展的切入点。 通过雨水的收集、以及不整地耕作法和覆盖作物等保护性农业技术对降雨善加利用,为发展生产性企业奠定了基础,而这对提高粮食的自给自足以及发展农村经济而言具有至关重要的作用。一年生作物的产量很快就能够实现增长。而对多年生作物而言,其影响需要经过几年才能显现。然而,只要是管理得当,在水源充足、或者是土壤湿润度及土壤肥力管理均能跟上的情况下,就有可能带来可观的收益。

  当然,水源的储集并不仅仅是修建水窖、大坝、开井或建造水箱那么简单。这是一个缓慢的过程,是一个需要创造精神的过程。这一过程中,需要组织各个部落开展蓄水工作、并对其进行维持和管理。项目的各个环节都需要部落的紧密配合。并且还需要建立一个能够持续公正地共享水源的体系。而这些,也正是为什么该项目需要部落参与的原因。

  因此,关键就在于要使农民和社区明白并坚信水资源的储集能够真正发挥作用。政府应该成为引导者,而不是实施者,应该在水资源储集的推广工作中发挥重要作用。政府还可以号召科研机构设计出更加合理的储水系统。但是,政府最重要的角色就是从财政上为城乡地区开展储水项目提供奖励和资助。

 

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