Impacts of the local land-use system in a semi-arid region of northeastern China on soil properties, crop growth, and weed communities     

T. Miyasaka  T. OkuroH. Zhao  X. ZhaoX. Zuo  K. Takeuchi 《Journal of Arid Environments》2011,75(11):1155-1163

We examined changes in soil properties, crop biomass, and weed communities in the Horqin Sandy Land of China to elucidate cropland degradation. We studied three local cropland types having periods of cultivation of up to 20 years: maize cropland on lowlands without irrigation (nonirrigated lowland), maize cropland on flat sandy lands with irrigation (irrigated flatland), and bean-centered cropland on sand dunes without irrigation (nonirrigated dunes). Soil properties and crop biomass were more degraded in nonirrigated lowland and nonirrigated dunes than in irrigated flatland. Weed communities in the nonirrigated croplands were the type that become established in drier conditions, whereas wetland weeds were more abundant on irrigated flatland. Trends of change in each indicator did not always occur in parallel and differed statistically among the cropland types. Monitoring these indicators within the context of local land-use systems can provide scientific evidence on which to base local management practices or recommendations for change.  相似文献   

Are you Wittfogel or against him? Geophilosophy,hydro-sociality,and the state     

《Geoforum》2014

Recent explorations of the “hydrosocial” cycle draw inspiration from Wittfogel’s basic concern with politics, power, and centralized authority, but move well beyond the limitations of previous scholarship. Most importantly, they have (re)introduced a conception of the social into the hydrological, and grappled with water’s materiality in ecumenical and creative ways. Understanding hydro-sociality requires an ontological approach to matter, flux, and flow. Water is the “universal solvent,” which makes it infinitely capable of mutation and connection. Yet, such indeterminacy proves difficult to capture in research and writing. Here I pinpoint some of the politico-discursive strengths of the hydrosocial approach, and also where I think its already strong ontological inclinations could be further developed. I draw from work in the area of “geophilosophy” as a way to explore hydro-sociality as a nonlinear process, developing a historicized account of irrigation politics, the flows of matter, and nonlinear dynamics in northwest Mexico’s Río Mayo Valley.  相似文献   

Determination of water balance equation components in irrigated agricultural watersheds using SWAT and MODFLOW models : A case study of Samalqan plain in Iran          下载免费PDF全文

Shima Nasiri  Hossein Ansari  Ali Naghi Ziaei 《地下水科学与工程》2022,10(1):44-56

Increasing water demands,especially in arid and semi-arid regions,continuously exacerbate groundwater as the only reliable water resources in these regions.Samalqan watershed,Iran,is a groundwater-based irrigation watershed,so that increased aquifer extraction,has caused serious groundwater depletion.So that the catchment consists of surface water,the management of these resources is essential in order to increase the groundwater recharge.Due to the existence of rivers,the low thickness of the alluvial sediments,groundwater level fluctuations and high uncertainty in the calculation of hydrodynamic coefficients in the watershed,the SWAT and MODFLOW models were used to assess the impact of irrigation return flow on groundwater recharge and the hydrological components of the basin.For this purpose,the irrigation operation tool in the SWAT model was utilized to determine the fixed amounts and time of irrigation for each HRU(Hydrological Response Unit)on the specified day.Since the study area has pressing challenges related to water deficit and sparsely gauged,therefore,this investigation looks actual for regional scale analysis.Model evaluation criteria,RMSE and NRMSE for the simulated groundwater level were 1.8 m and 1.1%respectively.Also,the simulation of surface water flow at the basin outlet,provided satisfactory prediction(R²=0.92,NSE=0.85).Results showed that,the irrigation has affected the surface and groundwater interactions in the watershed,where agriculture heavily depends on irrigation.Annually 11.64 Mm3 water entered to the aquifer by surface recharge(precipitation,irrigation),transmission loss from river and recharge wells 5.8 Mm3 and ground water boundary flow(annually 20.5 Mm³).Water output in the watershed included ground water extraction and groundwater return flow(annually 46.4 Mm³)and ground water boundary flow(annually 0.68 Mm³).Overally,the groundwater storage has decreased by 9.14 Mm3 annually in Samalqan aquifer.This method can be applied to simulate the effects of surface water fluxes to groundwater recharge and river-aquifer interaction for areas with stressed aquifers where interaction between surface and groundwater cannot be easily assessed.  相似文献   

Water resources development and management in the Cuddapah district, India     

M. Ramakrishna Reddy  N. Janardhana Raju  Y. Venkatarami Reddy  T. V. K. Reddy 《Environmental Geology》2000,39(3-4):342-352

 Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological (surface and groundwater) and geochemical aspects have been studied for the development and management of water resources in drought-prone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About 91 000 ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about 47 000 ha is irrigated by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators for the irrigation practices. Groundwater assessment studies revealed that 584 million m³ of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or the application of fertilisers. Received: 10 June 1998 · Accepted: 15 November 1998  相似文献   

宝鸡─常兴源农灌区斜坡环境的变异研究     

杜岳鸿 《地球科学与环境学报》1996,(1)

在黄土台源农灌区，其天然斜坡环境常被农田灌溉所变异，形成农灌工程地质斜坡环境。在此种环境中，斜坡的变形和破坏常被诱发、激活和加剧，从而产生了新的农灌斜坡环境工程地质问题。若对其进行治理，必须从农田灌溉诱发、激活和加剧灌区内斜坡变形和破坏这一观点进行考虑．本文试图以宝鸡─常兴源农灌区斜坡的环境工程地质问题为例，对上述观点进行阐述。  相似文献   

基于高光谱的河套灌区农田表层土壤质地反演研究   总被引：2，自引：0，他引：2  

白燕英  魏占民  刘全明  郭桂莲  刘霞 《地理与地理信息科学》2013,29(5)

以河套灌区解放闸灌域农田表层0～10 cm土壤为研究对象,研究风干土样的不同粒级含量与光谱特性关系,遴选出反映土壤粘粒、粉粒、砂粒含量各自敏感的光谱波段,分别建立土壤粘粒、粉粒、砂粒含量与敏感波段的一元线性回归模型和BP神经网络模型,模型验证结果表明:土壤粘粒、粉粒、砂粒含量的一元回归模型与BP神经网络模型精度基本一致,且都在85％以上.该研究结果可为应用高光谱遥感图像大范围识别河套灌区的土壤质地提供理论依据.  相似文献   

灰色GM(1,1)模型研究关中灌区地下水位变化规律     

李云峰  田春声 《地球科学与环境学报》1993,(4)

关中平原的渠灌区地下水位上升是普遍现象,严重时会造成一系列环境水文地质问题。本文通过建立灰色GM(1,1)模型研究了宝鸡峡灌区下游的地下水位变化规律,并进一步预测了其发展趋势。  相似文献   

The water regime of the Monegros playa-lakes as established from ground and satellite data     

Carmen Castaeda  Juan Herrero 《Journal of Hydrology》2005,310(1-4):95-110

The Monegros playa-lakes are isolated saline wetlands, locally named ‘saladas’, situated in a vulnerable semi-arid territory where agricultural expansion threatens the natural hydrologic cycle with regular artificial flooding, risking the survival of a valuable natural resource. This study aims to examine the water regime of these playa-lakes from climate data and available hydrologic records. These records are historical and limited to a series of weekly measurements of depth and of water extent extracted from Landsat imagery. We have characterized the hydrological behavior of the playa-lakes by treating ground and satellite data separately. For this purpose, the playa-lakes are first grouped according to the water occurrence episodes. Then their hydrologic status is related to the previous rainfall and also to ET₀, since there is a lack of local records of wind as well as brine or fresh water evaporation. The northern playa-lakes respond to rain faster than the southern ones. All playa-lakes have a significant relationship between water occurrence and rainfall accumulated within 180 days prior to an observation. A significant relationship between ET₀ and water occurrence was found for a shorter 15-day accumulation period. Quantifying the current water regime now is critical for monitoring the effects of expanding irrigation in adjacent lands. Remote sensing is well-suited to an environmental assessment for regions of difficult access with the added benefit of lowered field measurement cost. The hydrological data from the Monegros playa-lakes could be integrated with other playa environments worldwide to compare regionally specific climate conditions.  相似文献   

基于GRACE数据的天山阿克苏河流域水储量变化分析     

王志成  张辉  李万江  邓海军 《沙漠与绿洲气象(新疆气象)》2017,11(6):1-8

水储量变化可视为气候变化对水文系统影响的指示器。基于GRACE数据,结合气候数据和冰川积雪数据,分析了近10 a年来阿克苏河流域的水储量变化。研究结果表明:(1)过去10 a间阿克苏河流域的水储量呈递减趋势,减少速率为-0.12±0.85 cm/a,且春季表现为正距平,而秋季表现为负距平;(2)山区冰川退缩和积雪消融是该流域山区水储量减少的主要原因,近半个世纪以来冰川物质平衡为负平衡,同时近十年来积雪面积递减速率为-24 km~2/a;(3)阿克苏河流域的耕地面积的迅速增加导致了地下水过度超采,是绿洲区水储量减少的主要驱动因子。  相似文献   

Contesting expertise: The politics of environmental knowledge in northern Indian groundwater practices     

Trevor Birkenholtz 《Geoforum》2008,39(1):466-482

The world is facing a severe water crisis. According to the UN, by 2025 50% of the world’s population will face water scarcity. In India, where 70% of irrigation and 80% of domestic needs are met with groundwater, demand for this resource is expected to exceed supply by 2020. This has led to recent calls for groundwater governance reforms within India, and specifically within the state of Rajasthan, where no regulation exists today. The success of these reforms hinges on the interaction of the state and its agents with local users and managers of groundwater resources. Underpinning these encounters, though, are tensions between local and state forms of groundwater knowledges. The question analyzed here is in what ways do conflicting environmental knowledges adversely affect the management of overexploited groundwater resources in water-scarce India? To address this question, I examine the coevolution of pre-colonial, colonial, and post-independence groundwater and irrigation knowledges and technologies in Rajasthan, India to expose the ways that they are produced, contested, legitimated, and hybridized. The paper argues the following three claims. First, the relationship between the state and local producers of groundwater knowledge practices is non-linear and porous. For instance, the way that state subjects experience the state is uneven because within and in-between historical moments the state may attempt to assimilate, reorganize, plagiarize, or disparage local knowledge. Second, these attempts produce or exacerbate existing historically rooted tensions between farmers and state groundwater engineers. But in response, farmers often seek out non-state avenues of expertise, such as tubewell drilling firms. This results in the further hybridization of knowledge practices and also in the present-day marginalization of the state. Third, the relationship between farmers and the state is further strained because of a current lack of state visibility in the study area and also because the state continues to “see like a state”. These shifting meanings and power relations around groundwater and irrigation knowledges produce tensions that will undoubtedly negatively impact future groundwater governance strategies.  相似文献