该区土壤表层的盐分除了当地成土母质自然形成的之外

1、该区土壤表层的盐分除了当地成土母质自然形成的之外，很大一部分来自于灌溉水，也就是黄河水。因此，研究黄河水的含盐量对明确当地灌区盐碱形成的原因有重要作用。该区黄河水的含盐量约为0.4-1.7g/L，PH值约在8.1-8.8之间，主要包括Na+、Mg2+、K+、Ga2+、SO42-、Cl-、HCO3-、CO32-等离子，其中Na+约为40mg/L，占离子总量的10%。灌溉后，由于强烈的蒸发，一部分盐分被留在了农田之中，据研究，该区仅有不到70%的盐分被排出，30%的盐分都积存在了灌溉农田里，农田平均积盐3thm²。Saline on the topsoil in this region

2、comes from naturally formed local soil parent materials ,but mostly from irrigation waterwater from Huang He River(yellow river) ,therefore, to better understand how saline and alkaline in the soil of the region have formed ,studying saline and alkaline in the soil of this region is extremely import

3、ant .Water from Huang He River, whose salinity stands at 0.4-1.7g/L and PH value ranges from 8.1 to 8.8,mainly consists of ions ,such as Na+、Mg2+、K+、Ga2+、SO42-、Cl-、HCO3-、CO32-, .Of these, Na takes up 40mg/L, ten percent of the total ion amount. After irrigation, a portion of salt remains in farmland

4、s because water evaporates quickly. It has been studied that salinity in farmlands averages 3thm²,because less than 70 percent of salinity has been discharged while 30% has remained in the irrigated farmlands 灌水携带的泥沙及其产生的灌溉淤积物主要危害就在于造成灌溉农田的沙化，且淤堵渠道，不仅占用部分良田，还将会造成当地沙漠化，出现涝碱。据研究，该区黄河水含沙量约为100-400

5、kg/m³，进一步加剧了该区农田的沙化和盐渍化，但是，如果运用得当，泥沙也会改善当地的土壤理化性质，改善土壤孔隙状况，提高农田土壤肥力。Silt carried by irrigating water and deposited sediments caused by irrigation, which intensify irrigated farmlands desertification and block irrigation channels, not only take up some fertile farmlands, but cause local region d

6、esertified and waterlogging . The study shows that sands in Huang He River approximately have reached 100-400kg/m³,which makes farmlands more desertifying and salinizing. But if used properly, silt can change soil properties, improve the condition of soil pores and make farmlands more fertile地下

7、水中的盐分和底土中的盐分是土壤表层积盐的主要来源，因此，地下水位抬高是该区盐碱的主导因素，而地下水位的升降与灌溉密切相关。据研究，该区灌水期比非灌水期地下水位升高0.85-1.32m，且表层土壤盐分随灌溉量增大而加剧。由于该区灌溉主要依靠引进大量黄河水，忽视地下水的开采利用，导致地下水位连年上升。目前研究认为，该区地下水位临界值在1.5-2.4m，超过此值，易发生盐碱，目前该区地下水位多在2-5m之间。该区地下水含盐量不均衡，重度一般在10g/L，也有的区域小于1 g/L。主要离子为Na+、Mg2+、K+、Ga2+、SO42-、Cl-。因当地气候干燥，蒸发量大，引发地下水中盐分向土壤表层迁移，

8、加剧了土壤盐渍化程度。据研究，该区经过3-5年的引水灌溉后，土壤表层就会产生积盐现象。据内蒙古自治区水利厅对河套灌区盐分动态观测资料分析，耕地潜水位上升10cm , 0-100 cm土层昼夜积盐量达0. 0705-0 .1005t/hm2 ，盐荒地可达0. 3000-0.4005 t/hm2。Topsoil salt mainly comes from underground water and bottom earth, therefore, the main factor that soil in this region becomes saline and alkaline is the

9、 rising of underground water level. From this aspect, the rising and lowering of underground water level is closely linked with irrigation. The study shows that underground water level in the irrigation phase rises by 0.85-1.32m, compared to that in non-irrigation phase, meanwhile, salt in the topso

10、il increases with the irrigation amount increasing. Because irrigating water in this region mostly comes from water in Huang He River, underground water has been ignored to be used ,which causes the rising of underground water level year in year. According to a recent study ,the bottom line of under

11、ground water level in this region should stand at 1.5-2.4m ,if water overpasses this line ,alkalinity and salinity in water are likely to occur, ,actually, underground water level rises to 2-5m at present, So salinity and alkality in underground water of this region distribute unevenly .Normally, th

12、e density of water is 10g/L,some of which is less than 1 g/L and water ions consist of Na+、Mg2+、K+、Ga2+、SO42-、Cl-。 Water evaporates quickly when its dry, which makes salinity in water will divert into topsoil, intensifying soil salinity. The study shows that salification on topsoil takes place when

13、irrigation has been carried out for three to five years. The study on soil salinity of irrigated area in He Tao conducted by Mongolian water conservancy bureau shows that underground water table has risen by 10cm,0-100 cm and soil salification at daytime and night has reached 0.0705-0 .1005t/hm2 ,sa

14、line waste lands 0. 3000-0.4005 t/hm2过量灌溉是该区耕地盐碱化的最主要原因。过量灌溉会增加进入土地的盐分，并提高地下水位，水随盐来，促进地表积盐。黄河是中国的母亲河，冲积平原适于原始农牧业的发展，早在6000多年前，流域内已开始出现农事活动。战国初期，黄 河流域开始出现大型引水灌溉工程。此后数千年，该地区的人们都开渠灌田，灌溉面积逐渐扩大。中华人民共和国成立后，该区发展进入新阶段，土地开发强度逐渐增大，许多林地和草地也变成了灌溉农田，至上世纪90年代末，共增加灌溉面积约200万公顷。黄河上游是生态脆弱区，蒸发量大，随着地表植被的破坏，最终导致了盐碱化。近年来

15、，由于气候的暖干化、水资源的短缺以及社会经济的迅速发展和人口增长对水的需求日益增加，黄河水资源供需矛盾不断加剧，灌区引水量逐渐减少，加上灌区内存在配套工程老化现象，灌溉面积有逐步萎缩的趋势。这又意味着会有大量撂荒地出现，撂荒土地由于没有灌溉排盐和农艺治盐措施，土壤表层将会出现大量积盐，生态系统得不到修复，最终将导致严重盐碱化。The main reason for salinization and alkalization of farmlands is over-irrigation, which increases salinity of lands, lifts up undergrou

16、nd water level and accelerate the formation of topsoil salification. Reaches of the Yellow River, referred as “the mother river “,belong to a basin area which is good for the development of primitive agriculture and animal husbandry. As early as over 6000 years, farming production was engaged in the

17、 basin are and large irrigation projects began to be carried out in the early warring states period, since when people living in this area irrigated their farmlands .After the foundation of PRC in 1949,a new phase came into this area where many forests and grasslands were changed into farmlands with

18、 more lands reclaimed .By the end of the 1990s ,the total irrigated area was about 2 million hectares . The upper reaches area of Huang He River has been salinized and alkalized due to vegetation devastation and the fragility of local nature conditions. In recent years, dry and warm climate, deficie

19、ncy in water resources ,demands for water increased the contradiction between supply and demand of water resources in Huang He River with fast development of social economy and the growing of population ,therefore, irrigated area tends to be shrinking with irrigated water amount deceasing and irriga

20、ted equipment aging ,which means there are a number of waste lands to be uncultivated. The uncultivated waste lands will have a great deal of salification on their soil surface layers and be salinized seriously because salt in the soil surface layers isnt discharged by irrigation as well as no salin

21、ity control measures are not taken.该区灌溉每年平均引黄河水量约为150-180亿m³，占据黄河径流量的35%左右。该区所在生态需水量约为160亿立方米，另外，黄河还要保证中下游用水，因此，该区引水量偏多，使上游地域引排水没有达到平衡状态，积盐作用显著，另外还造成了当地水土流失，河道淤积等情况。近年来，国家对此有了一定的研究和认识，加上黄河上游气候暖干化，水量逐渐减少，国家开始降低上游灌区的引水定额，减少了15%左右 ，随着灌溉水量的减少，当地应对措施不足，土壤积盐有所增加，导致生态环境恶化，土地盐碱化、沙化，植被覆盖度降低，湖泊、沼泽面积大幅度减少

22、，土壤蓄水能力和含水量下降，而土壤蓄水能力和含水量下降又进一步促使环境恶化，土地盐碱化、沙化，植被破坏，往往造成恶性循环。The volume of water diversion from Huang He River which is used to irrigate in this area averages 15-18 billion m³annually, taking up around 35% of volume of runoff.The volume of water that is needed in this area stands at 16 billion

23、cubic meters, which ,additionally , ensure to satisfy the need of people in middle and lower reaches of river, due to more volumes of water diversion in this area, the balance was changed, soil satification serious, soil and water lost heavily ,water bed blocked by silt. In recent years ,Chinese gov

24、ernment began to reduce 15 percent of the volume of water diversion in upper reaches of river .when the volume of water discharge was reduced ,salification in soil surface layers began to increase because strategies taken by local government to deal with these problems are insufficient ,which makes

25、environment degraded, land salinizing and desertifying, the vegetation coverage decreased, lake and marsh area substantially reduced , water holding capacity and moisture content in soil going down.该区灌溉水的利用效率较低，不但造成了灌溉水的浪费，且造成了该区整体空间水的过饱和，使地下水位居高不下，土壤积盐严重。据研究，该区水资源利用系数仅0.3-0.45，综合灌溉定额一般在4500-9000m³/hm²之间，河套灌区局部区域甚至高达9000-19500m³/hm²，而相关研究显示，油葵灌溉1050 m³/hm²，玉米灌溉3150 m³/hm²时产量最高，该区灌溉定额过高，而适中的储水灌溉定额，不仅有利于作物的生长，还有利于灌溉水分利用效率的提高。另外，据研究，该区若配合渠系防渗等工程措施，可使渠系水利用系数从055提高到08。Due to the lower efficiency of utilization of irrigated water