To solve the problems of the poverty in rural areas and raise the output efficiency of agriculture, policy is the primary factor. Guiding by good policies, the design of agricultural structure and management technolog...To solve the problems of the poverty in rural areas and raise the output efficiency of agriculture, policy is the primary factor. Guiding by good policies, the design of agricultural structure and management technology are the two main technical supports for agricultural development. The authors apply the model to determine the consequences of four so-called poverty alleviation strategies： （i） intensification of production, （ii） diversification of livestock production, （iii） land expansion, and （iv） an exit from agriculture, with a set of regional poverty and biodiversity indicators. Diversification seems to be the most promising poverty reduction strategy, but requires an efficient use of animal manure in cropping systems to avoid environmental problems. Improved nutrient management in cropping systems is effective in reducing the regional nitrogen surplus, but less effective in increasing per capita income. The exit strategy is beneficial for reducing poverty and achieving biodiversity goals, but may have important social consequences, which are not addressed in this study. Further reduction of rural poverty is hampered by labor constraints during the harvesting period of high value crops, such as vegetables and fruits, which calls for research and development in the field of agricultural mechanization.展开更多
Probable maximum precipitation(PMP) is widely used by hydrologists for appraisal of probable maximum flood(PMF)used for soil and water conservation structures, and design of dam spillways. A number of methods such as ...Probable maximum precipitation(PMP) is widely used by hydrologists for appraisal of probable maximum flood(PMF)used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper,PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III(LP-III) distribution. Goodness of fit(GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall(HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor(K_m) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and K_m values varies from 2.54 to 4.68. The coefficient of variability(C_v) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization(MM) approach. In the hydro-meteorological approach, moisture maximization(MM) and wind moisture maximization(WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.展开更多
基金the Project (ICA4-CT-2001-10055)supported by the European Economic Commissionthe Project (2006039106) supported by Post Doctor-ate Foundation of China
文摘To solve the problems of the poverty in rural areas and raise the output efficiency of agriculture, policy is the primary factor. Guiding by good policies, the design of agricultural structure and management technology are the two main technical supports for agricultural development. The authors apply the model to determine the consequences of four so-called poverty alleviation strategies： （i） intensification of production, （ii） diversification of livestock production, （iii） land expansion, and （iv） an exit from agriculture, with a set of regional poverty and biodiversity indicators. Diversification seems to be the most promising poverty reduction strategy, but requires an efficient use of animal manure in cropping systems to avoid environmental problems. Improved nutrient management in cropping systems is effective in reducing the regional nitrogen surplus, but less effective in increasing per capita income. The exit strategy is beneficial for reducing poverty and achieving biodiversity goals, but may have important social consequences, which are not addressed in this study. Further reduction of rural poverty is hampered by labor constraints during the harvesting period of high value crops, such as vegetables and fruits, which calls for research and development in the field of agricultural mechanization.
基金supported by Centre of Excellence in Water Resources Engineering,University of Engineering and Technology Lahore
文摘Probable maximum precipitation(PMP) is widely used by hydrologists for appraisal of probable maximum flood(PMF)used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper,PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III(LP-III) distribution. Goodness of fit(GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall(HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor(K_m) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and K_m values varies from 2.54 to 4.68. The coefficient of variability(C_v) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization(MM) approach. In the hydro-meteorological approach, moisture maximization(MM) and wind moisture maximization(WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.
