东江是粤港澳大湾区最重要的水源地,担负着香港地区、深圳和广州3个超大城市的供水任务。东江流域光、热资源充足,雨量充沛,是中国森林覆盖率最高的地区之一,其自1980年以来由于自然因素、政策和经济发展等原因,流域的土地覆盖发生了显...东江是粤港澳大湾区最重要的水源地,担负着香港地区、深圳和广州3个超大城市的供水任务。东江流域光、热资源充足,雨量充沛,是中国森林覆盖率最高的地区之一,其自1980年以来由于自然因素、政策和经济发展等原因,流域的土地覆盖发生了显著变化,尤其是东江流域面积占比最大的森林的变化更加明显。因此,如何科学规划设计造林工程,依据潜力分析改造水源林已成为社会热点问题。该研究基于1980—2020年东江流域30 m分辨率的土地利用、土壤等数据,结合东江源测站数据和社会经济指标数据,利用空间分析和因子分析等方法,探索东江流域1980—2020年森林覆盖的时空变化及驱动机制,同时对水源林改造的未来潜力进行了分析。①1980—2020年东江流域森林持续减少,总减少量为998.81 km 2,变化多集中于南部和北部,流域北部大量林地转化为耕地,流域南部大量林地转化为城乡、工矿、居民用地;②1980—2020年,影响林地面积变化的因素中,常住人口数量、人口密度、GDP、第二和第三产业产值、工农林业产值、社会消费品零售总额、固定资产投资额、城镇登记失业率等因素占主要成分;③东江流域未来可改造林区域面积为5365 km 2,改造潜力多集中于流域北部及流域东南部。近40 a内东江流域森林面积持续减少,人为活动影响强烈,水源林改造潜力巨大。展开更多
Kuwait, one of the gulf council member countries, situated in the Northeastern part of the Arabian Peninsula, experiences hyper-arid desert environmental condition due to the geographical location. Kuwait faces many c...Kuwait, one of the gulf council member countries, situated in the Northeastern part of the Arabian Peninsula, experiences hyper-arid desert environmental condition due to the geographical location. Kuwait faces many challenges in the sustainable development of the agricultural sector due to the scarcity of arable land, water resources and high rate of land degradation. So it is essential to emphasis the efficient use of the available water and soil resources in a sustainable manner and also to rehabilitate the degraded land using proper rehabilitation techniques. This study concentrates on the water harvesting and organic mulching （e.g., using date palms） methods. The study area is an artificial playa （2,500 m2）, formed through the dumping of the gravel quarries in December 2003. The application of the water harvesting and mulching technique in the study showed an improvement of soil physical properties. The average infiltration capacity has increased from 74 cm3/min to 112 cm3/min. The average difference in volume of infiltrated water was 33.5%. The bulk density and porosity of the control plot was 2 g/cm3 and 27%, respectively; while that of the treated soil was 1.5 g/cm3 and 44%, respectively. The moisture content of the treated soil was increased to 50%, more than control soil at depth 40-60 cm, and also there was a significant increase in organic matter. The temperature of the treated soil was 2 ℃ lower than the control soil at a depth of 60 cm. This study conserved the irrigation water through reducing the proportion of soil evaporation and thus creating an optimum condition for the plant growth.展开更多
ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units ...ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.展开更多
文摘东江是粤港澳大湾区最重要的水源地,担负着香港地区、深圳和广州3个超大城市的供水任务。东江流域光、热资源充足,雨量充沛,是中国森林覆盖率最高的地区之一,其自1980年以来由于自然因素、政策和经济发展等原因,流域的土地覆盖发生了显著变化,尤其是东江流域面积占比最大的森林的变化更加明显。因此,如何科学规划设计造林工程,依据潜力分析改造水源林已成为社会热点问题。该研究基于1980—2020年东江流域30 m分辨率的土地利用、土壤等数据,结合东江源测站数据和社会经济指标数据,利用空间分析和因子分析等方法,探索东江流域1980—2020年森林覆盖的时空变化及驱动机制,同时对水源林改造的未来潜力进行了分析。①1980—2020年东江流域森林持续减少,总减少量为998.81 km 2,变化多集中于南部和北部,流域北部大量林地转化为耕地,流域南部大量林地转化为城乡、工矿、居民用地;②1980—2020年,影响林地面积变化的因素中,常住人口数量、人口密度、GDP、第二和第三产业产值、工农林业产值、社会消费品零售总额、固定资产投资额、城镇登记失业率等因素占主要成分;③东江流域未来可改造林区域面积为5365 km 2,改造潜力多集中于流域北部及流域东南部。近40 a内东江流域森林面积持续减少,人为活动影响强烈,水源林改造潜力巨大。
文摘Kuwait, one of the gulf council member countries, situated in the Northeastern part of the Arabian Peninsula, experiences hyper-arid desert environmental condition due to the geographical location. Kuwait faces many challenges in the sustainable development of the agricultural sector due to the scarcity of arable land, water resources and high rate of land degradation. So it is essential to emphasis the efficient use of the available water and soil resources in a sustainable manner and also to rehabilitate the degraded land using proper rehabilitation techniques. This study concentrates on the water harvesting and organic mulching （e.g., using date palms） methods. The study area is an artificial playa （2,500 m2）, formed through the dumping of the gravel quarries in December 2003. The application of the water harvesting and mulching technique in the study showed an improvement of soil physical properties. The average infiltration capacity has increased from 74 cm3/min to 112 cm3/min. The average difference in volume of infiltrated water was 33.5%. The bulk density and porosity of the control plot was 2 g/cm3 and 27%, respectively; while that of the treated soil was 1.5 g/cm3 and 44%, respectively. The moisture content of the treated soil was increased to 50%, more than control soil at depth 40-60 cm, and also there was a significant increase in organic matter. The temperature of the treated soil was 2 ℃ lower than the control soil at a depth of 60 cm. This study conserved the irrigation water through reducing the proportion of soil evaporation and thus creating an optimum condition for the plant growth.
文摘ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.
