Rainwater Utilization for Sustainable Development in North China by Haisheng Mou
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Rainwater utilization for sustainable development in north China by Haisheng Mou China's population continues to grow, while her water problem. The frequent droughts, together with the growing water economy expands at an unparalleled rate. Can shortage, have prompted the villagers her water resources cope with the new of Yuanshi to adopt rainwater harvest- demands? Ancient rainwater harvesting ing techniques to address the immedi- ate problem, and for promoting devel- techniques may yield even more in the future. opment in general. Pilot project A COMBINATION OF the threat of ing for 53 per cent of the total, a figure As part of an ongoing pilot project, global warming, the ever-growing pop- which plummets during the spring about 50 household rainwater catch- ulation, and rapid economic develop- sowing period of April and May to ment systems have been installed in ment is likely to make regional water below 5mm, accounting for 1 per cent rural households in Yuanshi county. shortages progressively more serious in of the total. So, for the people of Each consists of around 100m2 of roof many semi-arid parts of northern China Hebei, spring often means drought, and courtyard surface catchment area, over the coming decades. This, in turn, resulting in restricted industrial and and a 5 to 6m3 rectangular sub-surface, may constrain development in a region agricultural production. Assessments cement rectangular tank, and a hand- which supports a population of tens of show that the rainwater resources of pump. To save money, the systems millions who depend primarily on sub- Yuanshi county are considerable, with have been designed to work without sistence agriculture for their survival. mean annual totals of about 387 mil- wire reinforcement or metal gutters; The increased utilization of rainwater lion cubic metres. Nevertheless, popu- the final unit cost is usually less than may be the only way to ensure sustain- lation growth and agricultural develop- US$ I00. A line of bricks laid on the able water-resource development in ment have led to a rapid rise in peo- sloping roof directs water into a plastic this region. With this in mind, ple's need for water; as a result, water downpipe, and into the tank. So far, the researchers from Shijiazhuang's Insti- shortages have been increasing since systems have been highly effective, tute of Agricultural Modernization the 1970s. and the families - who work on have conducted experiments with vari- Three main rivers cross Yuanshi installing the systems and provide cer- ous kinds of rainwater harvesting tech- county; in the 1950s, each flowed with- tain materials - are very enthusiastic. niques in Yuanshi county, a part of out interruption but, by the 1960s, only Hebei Province. seasonal flows were being recorded. Since the 1970s, the rivers have dried Techniques down the ages Yuanshi - land and rainfall up, and the people have had to dig Although there is a long history of wells for their water supplies. Recently, rainwater utilization in Yuanshi county, Yuanshi county is typical of north however, the water level of these wells and traditional techniques have contin- China. The western part is distin- has been falling very quickly, and peo- uously developed, it has still to achieve guished by undulating hills and valleys ple are beginning to worry about the widespread popularity. Before the while, in the east, a sloping alluvial plain runs up to the Taihang mountains. Both the plain and the terraced lower slopes of the mountains are character- ized by intensive, mixed semi-subsis- tence agriculture based on wheat, maize, bean, and vegetable production. The area has a continental, mon- soonal semi-arid climate with a mean annual temperature of 12.6°C - rang- ing between a summer maximum of 42°C and a winter minimum of -25°C. The mean annual rainfall is 589mm, and its distribution in time and space is uneven. The precipitation varies greatly between years; in the hills, 1963 saw a maximum of 1412mm; while in 1972, a minimum of only 189mm was recorded on the plain. Water demand Rainfall distribution throughout the year is also uneven. The mean rainfall in July and August is 304mm, account- Yuanshifamilies have welcomed the catchment systems enthusiastically. WATERLINES VOL. 14 NO.2 OCTOBER 1995 19 1950s, the 'first- divided into small level' utilization of and medium-sized rainwater played reservoirs with a the major role, as common capacity various small pro- of around 100 jects for collecting 000m3• and storing rainwa- Silt arresters ter were con- These are built in structed. the middle and Subsequently, upper reaches of pond excavation, valleys, mainly to dam construction, form small terraces and wells became in the valley bot- the main forms of toms of mountain rainwater utiliza- areas, thus enourag- tion. At present, the ing the utilization county is home to of floodwaters in more than 2000 the wet season by schemes for col- increasing soil- lecting and storing moisture storage, rainwater, such as and to control soil dams, ponds, pools, and water loss. water cellars, and Snow collection dangwas. Small and spreading projects can be Collecting snow to found all over the spread on their hilly region. The fields is another total storage capac- way in which the ity of all the people of northern schemes is about China utilize the 100 million metres3 winter precipita- (about 25 per cent tion. They collect of the total rain- the snow from fall). The tech- roads and court- niques that local yards, and carry it people favour are: to the fields, where Water-jar well A they spread it over traditional method the winter wheat; it for rainwater uti- also increases the lization in the Tai- amount of water '" hang mountains. available for arable ~ The well (under- crops when the g> ground tank) is spring thaw arrives. i usually 1.5 to 3m in Roof·tank systems ~ diameter, between A method available 4 and 6m deep, and 'In the hills, the tanks are built into the rock ... mud linings prevent seepage '. to every family in is either circular or the area. From the the water-table level is high. It is easy square. The structure comprises a well roof, and via the collection trough and to dig ponds in soft rock and these are floor, a wall, and a semi-circular cover. downpipe, the rainwater enters a con- filled from groundwater seepage. The The well is made of mixed soils, crete, underground storage tank, typi- ponds are usually 3 to 10m wide, and bricks, and concrete. Its wall has a 0.2 cally with a volume of 6m3. In the past, to O.3m-thick seepage·proof layer; and around 10m deep. They also collect the roof-tank system provided water and store rainwater runoff which sup- there is a circular inlet in the wall for for washing clothes, irrigation, and for plies water both for irrigation and rainwater collected from tiled roofs and the family's pigs. The current dearth of drinking - by people and their live- the courtyard. The water-jar well is water resources has spurred on the peo- stock. mainly used to supply water for agri- ple to make further improvements to cultural production, domestic use, and Mini-dams These are built in small their catchment systems; now they can animals' drinking-water. valleys and gullies. A mini-dam com- usually supply drinking-water fit for Water tank Circular or square and prises waterproof walls and an outflow human consumption. widespread in this area for storing sur- pipe; it is easily built, does not need Recharging groundwater using face rainwater runoff. The tanks are seepage-proofing, and has a volume of floodwater The River Baisha is one of about 2m deep, and can store up to sev- less than 10 000m3. It is mainly used to the largest rivers in the county, yet it eral hundred cubic metres of rainwater. store rainwater in valleys and gullies, flows only in the wet season. In the hills, the tanks are built into the and it supplies water for agriculture Researchers who examined the ground- rock, with mud linings to prevent seep- and animal husbandry. water recharge resulting from the age (see photo) while, on the plain, Small reservoirs A key method of 1990s damming of the Baisha in Yuan- they are built using a three-soil mix. rainwater use, involving obstructing shi, found that the total recharge in the Ponds Because rainwater in the hills and storing floodwater. Depending on region was over 16 670 000m3. They infiltrates quickly into the sandy soil, its design capacity, the reservoir can be observed that the groundwater level 20 WATERLINES VOL. 14 NO.2 OCTOBER 1995 rose, on average, by 5.6m, benefiting II townships and 61 villages, within an area of 200km2. This meant that 1200 wells received extra water, and 783 wells - dry for many years - could be used again. Plans to dig over 300 new wells were shelved representing sav- ings of over 1.2 million yuans. Future strategies As outlined above, only around 25 per cent of Yuanshi's rainwater resources are currently uti- lized. Furthermore, only about half of the rainwater resources which could be '" used and developed easily A h II II' h T'h • . h" h 2000 d" I h d J: b . s a ow we In t e lGl ang rnountGlns - Yiuans I IS orne to over tra Itlona met 0 s ar~I' adt APresenht elOg for collecting and storing water. uti Ize. s t e water shortages increase in the regIOn, problem. In addition to developing so on is also needed. the growing water cnsls IS certain rainwater catchment systems for water to deepen.