Historical aspects of soil erosion in the Mejerda catchment,Tunisia     

Sihem Jebari  Ronny Berndtsson  Fethi Lebdi  Akissa Bahri 《水文科学杂志》2013,58(5):901-912

Abstract

Agricultural use and related water erosion may lead to significant changes in the sedimentological and hydrological characteristics of watersheds, and therefore negative consequences for rural development. This research aimed to put present-day soil erosion of the important Mejerda catchment into a historical context. The catchment of Wadi Mejerda in northern Tunisia has experienced soil erosion due to weather and human impacts for thousands of years. We used historical texts and results from archaeological research that go back to 1000 BC, as well as data collected during the last century. Soil erosion from different types of agricultural landscape management was analysed together with information on the soils' production potential, the hydrographic network and flood frequency. The results showed that water erosion has increased the hydrographic network by 65 km and increased the deltaic plain by as much as 15 km²/century. However, soil productivity has decreased significantly. Moreover, due to in channel sedimentation and river choking, the number of flooding occurrences has multiplied over the last century. Finally, it is shown that water erosion follows a specific cycle of degradation throughout the watershed. These findings should be considered for better water and soil management in the context of semi-arid areas.

Editor Z.W. Kundzewicz

Citation Jebari, S., Berndtsson, R., Lebdi, F., and Bahri, A., 2012. Historical aspects of soil erosion in the Mejerda catchment. Hydrological Sciences Journal, 57 (5), 901–912.  相似文献   

Estimation of phosphorus loads with sparse data for agricultural watersheds in the Czech Republic     

Tereza Beránková  Richard M. Vogel  Daniel Fiala  Pavel Rosendorf 《水文科学杂志》2013,58(8):1417-1426

Abstract

Agricultural watersheds in the Czech Republic are one of the primary sources of non-point-source phosphorus (P) loads in receiving waters. Since such non-point sources are generally located in headwater catchments, streamflow and P concentration data are sparse. We show how very short daily streamflow and P concentration records can be combined with nearby longer existing daily streamflow records to result in reliable estimates of daily and annual P concentrations and loads. Maintenance of variance streamflow record extension methods (MOVE) can be employed to extend short streamflow records. Constituent load regressions are used to predict daily P constituent loads from streamflow and other time varying characteristics. Annual P loads are then estimated for individual watersheds. Resulting annual P load estimates ranged from 0.21 to 95.4 kg year^-1 with a mean value of 11.77 kg year^-1. Similarly annual P yield estimates ranged from 0.01 to 0.3 kg ha^-1 year^-1 with an average yield of 0.07 kg ha^-1 year^-1. We document how short records of daily streamflow and P concentrations can be combined with a national network of daily streamflow records in the Czech Republic to arrive at meaningful and reliable estimates of annual P loads for small agricultural watersheds.

Citation Beránková, T., Vogel, R. M., Fiala, D. & Rosendorf, P. (2010) Estimation of phosphorus loads with sparse data for agricultural watersheds in the Czech Republic. Hydrol. Sci. J. 55(8), 1417–1426.  相似文献   

Predicting agricultural drought in eastern Rajasthan of India using NDVI and standardized precipitation index     

Dipanwita Dutta  N.R. Patel 《国际地球制图》2013,28(3):192-209

In the present study, prediction of agricultural drought has been addressed through prediction of agricultural yield using a model based on NDVI-SPI. It has been observed that the meteorological drought index SPI with different timescale is correlated with NDVI at different lag. Also NDVI of current fortnight is correlated with NDVI of previous lags. Based on the correlation coefficients, the Multiple Regression Model was developed to predict NDVI. The NDVI of current fortnight was found highly correlated with SPI of previous fortnight in semi-arid and transitional zones. The correlation between NDVI and crop yield was observed highest in first fortnight of August. The RMSE of predicted yield in drought year was found to be about 17.07 kg/ha which was about 6.02 per cent of average yield. In normal year, it was 24 kg/Ha denoting about 2.1 per cent of average yield.  相似文献   

日照市城乡建设用地增减挂钩工作的探讨     

邱中华  孙利刚 《山东地质》2012,(2):63-65

随着社会主义市场经济的发展,推进土地集约节约利用,促进城乡统筹发展,是当前和今后一个时期有效的利用现有土地资源,改善农村生产生活条件和环境、缓解建设用地供需矛盾的有效途径和手段。近几年来,日照市严格按照上级有关要求,规范开展了城乡建设用地增减挂钩试点工作,取得了显著成效。  相似文献   

呼伦贝尔春玉米生育期气候环境分析     

李飞  刘勇  敖丽良  张秀英  马建  郑丽娟 《内蒙古气象》2013,(1):32-34

利用呼伦贝尔市农区2012年生育期降水、温度、土壤水分以及玉米生长发育等资料,分析了气候环境对春玉米生长发育和产量的影响。结果表明:2012年春季雨水适宜,利于玉米春播生产;夏季水热同步,有利于玉米生殖生长和营养生长,提高了春玉米的产量。  相似文献   

土地质量地球化学评估与绿色产能评价研究:以吉林大安市为例   总被引：4，自引：0，他引：4  

王立胜  汪媛媛  余涛  杨忠芳  白荣杰 《现代地质》2012,26(5):879-885

做好土地资源数量管控,加强耕地质量管理和生态管护是当前的一项非常重要的工作。选择吉林省大安市东南区域为研究对象,进行土地质量地球化学评估,并融合污染元素进行农用地分等研究。结果表明研究区内评定为三等及以上的土壤占全区总面积的72.61%,研究区土地质量总体较好,优质和优良土地分布面积较大,主要为黑钙土,差等的土地主要为盐碱土或盐化草甸土。尝试性地将农用地分等成果中的产能评价和土地质量地球化学评估中的元素含量评价结合,开展了绿色产能评价。  相似文献   

河南省农用天气预报业务系统的设计与应用   总被引：4，自引：0，他引：4  

余卫东  张广周  张弘 《气象与环境科学》2011,34(3):79-82

根据农用天气预报内容和业务流程,确定了河南省农用天气预报业务系统结构和功能。该业务系统主要包括农用天气预报省级指导产品制作平台、市县订正平台和省级产品订正发布平台三个部分。通过该系统可以实现省级农用天气预报指导产品的制作和分发自动化,市县对指导产品的调取、订正和反馈,省级农业气象服务产品在市、县级实时共享。农用天气预报业务系统的开发和推广,提升了基层农业气象预报服务能力。  相似文献   

基于主成分和模糊C-均值聚类算法的农业水资源高效利用综合分区   总被引：1，自引：1，他引：0  

刘玉邦  梁川 《水文》2011,31(5):57-63

基于农业生态系统环境要素、水的资源属性、水资源的高效利用内涵、生产力水平、土地利用方式、种植结构及种植模式等因子,选取构建农业水资源高效利用综合分区的指标体系(16个定量指标、4个定性指标),采用主成分分析和模糊C-均值聚类算法为区划方法,对川中丘陵区进行量化分区。研究结果将川中丘陵区16个地级市和一个县级市(简阳)分为农业水资源较低利用区、农业水资源低效利用区、农业水资源中等利用区、农业水资源高效利用区和农业水资源较高效利用区5个区,这对南方季节性干旱区水资源利用规划有较强的借鉴作用。  相似文献   

改革开放以来中国农业政策效果的时空计量分析   总被引：1，自引：0，他引：1  

余建辉  张文忠  王岱 《地理学报(英文版)》2011,21(3):475-488

Since reform and opening up, how much contribution has China’s implementation of new agricultural policy made to agricultural output? This paper is trying to establish an agricultural policy output econometric model for doing a quantitative analysis of China’s new agricultural policy. The results show that China’s agricultural policies on agricultural output have an average contribution rate of about 7% since 1978, which is consistent with the OECD’s basic forecast. There are obvious temporal and spatial differences. Generally speaking, we can divide the contribution of agricultural policy into three periods, which are the start-up phase from 1978 to 1991 (14 years), the stationary phase from 1992 to 2002 (11 years) and the rising phase from 2003 to 2008 (6 years). In space, the contribution of agricultural policy underwent a process from the all-low in the start-up phase, the gradual increase in the stationary phase to the all-high in the rising phase. Northern and western regions are more sensitive to policies. There are three major factors that can affect the contribution of regional agricultural policies, which are the process of national industrialization strategy, terrain and the level of local finance.  相似文献   

粒子群神经网络混合模型在农用地分等中的应用     

马世发  何建华  念沛豪  张雄宇 《地理与地理信息科学》2011,27(1):105-108,115

针对常规农用地分等模型因子权重计算存在人为干扰和神经网络模型自身优化过程中易陷入局部最优的情况,该文综合了BP神经网络非线性权重数据挖掘特性和粒子群的全局优化能力,建立了农用地分等计算的粒子群神经网络混合模型(PSO-BP网络模型),并应用于广东省揭西县农用地分等计算中,发现PSO-BP网络模型能避免定级因子权重确定的人为干扰,同时具有较高的优化效率,应用效果较好。  相似文献