While most of us just think of rainbarrels hooked up to the gutters on your house, when we think of water harvesting, the concept has actually been around for thousands of years.
Climate Change is going to create more droughts in dry areas but it also will create more and stronger rain storms, because the warmer air can hold much more water. Farmers may have both droughts and floods. If it is possible to build catchments to store storm runnoff, that water can used to prevent crop failures in the dry times.
“As land pressure rises, more and more marginal areas in the world are being used for agriculture. Much of this land is located in the arid or semi-arid belts where rain falls irregularly and much of the precious water is soon lost as surface runoff. Recent droughts have highlighted the risks to human beings and livestock, which occur when rains falter or fail.
While irrigation may be the most obvious response to drought, it has proved costly and can only benefit a fortunate few. There is now increasing interest in a low cost alternative – generally referred to as “water harvesting”.
Water harvesting is the collection of runoff for productive purposes. Instead of runoff being left to cause erosion, it is harvested and utilized. In the semi-arid drought-prone areas where it is already practised, water harvesting is a directly productive form of soil and water conservation. Both yields and reliability of production can be significantly improved with this method.
Water harvesting (WH) can be considered as a rudimentary form of irrigation. The difference is that with WH the farmer (or more usually, the agro-pastoralist) has no control over timing. Runoff can only be harvested when it rains. In regions where crops are entirely rainfed, a reduction of 50% in the seasonal rainfall, for example, may result in a total crop failure. If, however, the available rain can be concentrated on a smaller area, reasonable yields will still be received. Of course in a year of severe drought there may be no runoff to collect, but an efficient water harvesting system will improve plant growth in the majority of years.” http://www.fao.org/docrep/U3160E/u3160e03.htm
There are essentially two ways to conserve rainwater. One is in-situ which treats the soil so it absorbs more of the water so there is less runnoff. This could be terracing, tilling perpendicular to the slope, deep tillage and use of compost. This helps but may do nothing if it doesn’t rain and there is drought.
The other way to conserve water is through water catchments. Small ponds can be made to store water when there is too much rain, and that can be saved for when there is too little. http://academicjournals.org/journal/IJWREE/article-full-text-pdf/785D07451159
Israel has gained a worldwide reputation for its ability to turn barren desert into useful and arable land. This article takes a look at the country’s top 10 eco-strategies.
- Looking to the ancients They lived in the Land of Israel more than 2,000 years ago in the heart of the Negev Desert, yet found a way to survive and thrive. How did the Nabateans build a sustainable community that provided food, firewood and fodder for animals?
- Making the most from the sun In developing nations, people still cut trees for firewood. This causes desertification from lack of vegetation to hold the soil and its nutrients in place. Rain washes away the topsoil, leaving worthless sand behind.
- Help fish swim in the desert Vast desert land does not need to go to waste when practical high-value crops –– especially alternative ones like aquaculture –– can very much thrive there. Professors Shmuel Appelbaum and Dina Zilber from Ben-Gurion University helped perfect a system to grow fish in the desert.
- Alternative crops in the sand As with aquaculture, a number of drought-tolerant crops can thrive in the hot desert sun. Fed with brackish or low-quality water, algae for either biofuels or neutraceuticals present a novel way to grow a high-value product on seemingly valueless land. Several Israeli companies and research institutions are working to create the optimal environment for this plant-based microorganism, as well as genetic engineering to make algae contain more lipids that can be transformed into biofuel.
- Green building If Israel is known for its expertise in building desert-adapted houses it’s because the blueprints were designed and tested in the desert by the Blaustein Institute. The school’s Desert Architecture and Urban Planning unitfocuses on homes that require no air-conditioning, even during the day when the heat is most intense.
- More crop per drop You can’t talk about Israel’s success in making the desert bloom without mentioning drip irrigation and the companies that have made Israel a farmer’s best friend in hot, dry climates. Unlike much of the innovation in Israel that starts in the lab or research institute, modern drip irrigation was pioneered in the field by farmers, and is widely used across Israel to get the best crops using the least water.
- Roots of research The government-owned agricultural research organization, the Volcani Institute in Beit Dagan, is known for producing genetic variants of plants that perform very well in less than ideal conditions.
- Afforestation If done correctly, tree planting can reverse desertification by supporting the earth as plant life grows its roots into the sand, and helps to create a cycle of nutrients that nourish the soil.
- Rain dancers Back in the 1950s, the Israeli government under Golda Meir founded MASHAV in order to share Israel’s newfound expertise in desert agriculture. MASHAV runs a variety of programs, but is best known for its training seminars in Israel and wherever needed –– Africa, the Middle East, South America, Central America, India, China — on techniques ranging from greenhouse management and irrigation to fish farming and dairy farming.
- Wastewater management Almost all of Israel’s successes listed above rest on the fact that Israel has been able to excel at wastewater managementon a scale that no other country has ever matched. A whopping 50 percent of Israel’s irrigated water comes from recycled wastewater, according to Berliner, and much of this recycles through JNF planted forests. The country that comes closest to Israel’s level of water reuse is Spain, which only reuses about 20% of its liquid resource. http://www.israel21c.org/top-10-ways-israel-fights-desertification/
Here is a video of how they can grow trees in the desert. https://www.youtube.com/watch?v=eK0nEV5dWBA
On the other hand some critics think that the Israeli miracle is because they are stealing water from the Palestinians. http://www.aljazeera.com/indepth/opinion/2014/03/israel-water-miracle-palestine-20143247252981587.html
Pumping water from underground aquifers can be used for irrigation. Continuous irrigation can result in the accumulation of salt which destroys the fertility of the soil. Using deep compost allows fungi to encapsulate the salt so it doesn’t damage the soild. There are surface aquifers that should be replenished each year by the rainfall, but there are also fossil aquifers that take thousands of years to replenish. Most aquifers all over the world are being depleted because they are being sucked out faster than they are replenished. Storing up flood waters helps replenish aquifers. http://www.wateronline.com/doc/options-to-replenish-depleting-groundwater-0001
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