共查询到20条相似文献，搜索用时 15 毫秒
1.
Land subsidence is a phenomenon that involves the lowering or settling of the earth's surface due to various factors. The land subsidence due to groundwater withdrawal over the world has been seen in many areas. A decrease in ground water level would cause an increase in effective stresses at clay layers which results consolidation of lower layers. Since about 1980, it has been proven that Kerman Province subsidence in Iran is due to extensive ground water withdrawal. Overdraft of groundwater, an increasing of about 6 times since 1969 to 1999, has caused a decline of about 28 m in groundwater level. The rate of subsidence recently is about 5-15 cm. for decline of about one meter in groundwater level. In Rafsanjan area, many problems such as increase in the salinity of groundwater, land subsidence and consequently earth fissures and cracks in buildings are caused by groundwater withdrawal. 相似文献
2.
This experimental study assesses the effects of event rainfall on soil erosion characteristics in terraced rice paddy fields. A 0.75-ha terraced paddy field located in Northern Taiwan was used to investigate the soil erosion under the regular cultivation of rice during two crop seasons. The environmental changes were investigated in the neighboring areas in which terraced paddy fields have been converted to other land usages. The annual rate of soil erosion calculated from the observed rainfall runoff and suspended solid contained was 0.77 ton/ha, which is significantly less than the erosion rate associated with upland crop cultivation reported by other research conducted in Taiwan. Experimental results also showed that the terraced paddy field retained the highest percentages of clay, silt, and organic matter's content, as compared to those of other upland crops, indicating that the topsoil was less susceptible to rainfall erosion under flooded conditions of rice-cultivation. The results of this study show that the rice-planted terraced paddy offers the highest level of soil conservation. The function of soil and water conservation in terraced paddy fields could be further increased by effective maintenance of embankment and to raise the height of the bund. Poor management, abandoned cultivation, and converse to other upland crops of terraced paddy fields are regarded as major contributors to increased soil erosion in mountainous areas. The government in Taiwan should formulate effective measures and maintain sustainable rice cultivation in the terraced paddies. 相似文献
3.
Rainfall is a major source for groundwater recharge. The response of groundwater level to rainfall is divided into quick and slow parts. This article presents a method to analyze the rainfall-induced quick groundwater-level (QGL) response. In the method, a technique of recursive digital filter was applied to splitting the rainfall-induced QGL response from a residual groundwater hydrograph in which the effects of both earth tide and barometric pressure were removed. The response of QGL to rain was simplified as a linear function and described by using a convolution of a rainfall sequence and a discrete Kernel function. Based on data of rainfall and corresponding QGL variations, the discrete Kernel function was determined via a linear system analysis. The method was applied to determining the discrete Kernel function and simulating the variation of QGL to rain at the station of Naba well in southwestern Taiwan. Comparison between the results of simulations and measurements of QGL variations shows that our proposed method can simulate the QGL response to rain with a value of root mean square error less than 4.26 mm. Based on the discrete Kernel function, an empirical, continue Kernel function was also proposed. 相似文献
4.
Mitsumasa Anan Kozue Yuge Yoshisuke Nakano Satiant Saptomo Tomokazu Haraguchi 《Paddy and Water Environment》2007,5(1):41-47
This study quantifies the effects of paddy irrigation water on groundwater recharge. A numerical model of groundwater flow
was conducted using MODFLOW in a 600 ha study site in an alluvial plain along the Chikugo River, located in southwestern Japan.
To specify the surface boundary condition, data on the land use condition stored in the GIS database were transferred into
a numerical model of groundwater flow. The simulated results were consistent with the observed yearly changes of groundwater
level. Thus, it was appropriate to use the model to simulate the effects of paddy irrigation on groundwater. To quantify these
effects, the groundwater level was simulated during the irrigation period when all farmlands in the study site were ponded.
In this situation, the groundwater level was 0.5 to 1.0 m higher, the ground water storage 20% larger, and the return flow
of the groundwater to the river 50% larger than in the present land use condition. 相似文献
5.
Although a lot of research has been performed on estimating irrigation water demand at the on-farm level, far less has been done on irrigation water demand for a region-wide basis, such as for a river basin or an area covering multiple river basins. The capture and management of the spatial variations in related data such as soil, climate, crops, and canal networks is the key to effective and efficient regional irrigation water demand estimations. The Geographic Information System (GIS), with its powerful spatial data management and analysis capabilities is used in this study to extend the scope of on-farm irrigation water estimation into a regional estimation. A command area covering several river basins in southern Taiwan was used to build a model prototype. The model framework shows the capability of the system to estimate regional irrigation water demand with most of the spatial variations preserved. The model also shows the capability for quickly reflecting changes in irrigation water demand in response to changes in cropping patterns, a feature that may be a necessary for regional water resource planning. 相似文献
6.
Climate change can have a serious impact on water resources. The main agricultural product in southern Taiwan is rice, the planting of which consumes far more water than other crops. This makes agriculture in Taiwan especially vulnerable to climate change. In this study, we used the generalized watershed loading functions (GWLF) hydrological model to simulate the discharge of the Kaoping River under climate change scenarios A2 and B2 as released by the Intergovernmental Panel on Climate Change. We discussed the potential impact of climate change on water resources based on the results of GWLF simulations carried out using rainfall and temperature data from five general circulation models (GCMs). The simulation results indicate that river discharge in the wet season increases significantly, and decreases in the dry season. The discharge variations from using the various GCMs as inputs fall within the range of ?26 to +15 % for the dry season and ?10 to +82 % for the wet season. The variation in available water will seriously impact the first period rice farming (the period between the beginning of January and the end of May) in southern Taiwan. Consequently, effective reduction in conveyance loss in the irrigation canal systems and proper fallowing of paddy fields will be the main challenges to Taiwan’s agricultural sector for alleviating the impact of climate change. For further decision making, we show the effects of adapting to climate change by various degrees of the following two methods: fallowing paddy fields to various degrees and reducing conveyance loss in irrigation canal systems. 相似文献
7.
Taiwan is a small island located in monsoon Asia with an annual precipitation exceeding 2,500 mm, which is 2.6 times the world average. However, water available for each person in Taiwan is less than one seventh of the world average due to Taiwan's crowded population and river basin characteristics. Steep land slope and uneven time and space distribution of rainfall have caused water resources problems. Providing a pure and plentiful supply of water for the people challenges the Water Resources Agency in Taiwan. History is a powerful tool for portraying the future. This paper discusses major themes in the review of water resources development over the last centuries. The changes in social-economic development, water resources infrastructure and demands of water are central to the discussion, with an eye to the plentiful and sustainable implications of water resources management in Taiwan. The water policy in the twenty-first century is also outlined.Dr. Hwang is the Advice of the Council for Economic Planning and Development (CEPD), Ministry of Economic Affairs (MOEA), Taiwan, Chairman of the Water Resources Committee, Chinese Institute of Civil and Hydraulic Engineering, a board member of the International Commission on Irrigation and Drainage (ICID) Chinese Taipei Committee, former chairman of the Chinese Society of Agriculture Engineering (CSAE), former director of Water Resources Agency (WRA), former director of the Taiwan Provincial Water Conservancy Agency (TPWCA), and former director of the Taiwan Provincial Water Conservancy Bureau (TPWCB). 相似文献
8.
Flooded paddy fields have many functions, including not only rice production, and ecological and environmental conservation.
This work estimates the extent of paddy field infiltration in Taiwan by adopting a one-dimensional Darcy-based soil/water
balance model SAWAH (Simulation Algorithm for Water Flow in Aquatic Habitats). A 10 cm thick plow sole layer with a hydraulic
conductivity of 0.03 cm/day, coupled with the soil texture and irrigation data obtained from 15 irrigation associations, is
used to estimate the volumetric amount of annual infiltration in Taiwan. Simulation results from SAWAH indicate that the plow
sole layer controls the movement of infiltrated water, with a rate about 1.8 billion cubic meters annually. The estimated
infiltration rate of 1.8 billion m3/yr comprises more than 40% of the annual infiltration recharge to ground water in Taiwan. Additionally, the amount of infiltration
recharge to groundwater is equivalent to 20 billion Taiwan dollars NT$ (or 0.65 billion US$) while the yearly rice crop production
is 35 billion NT$ (or 1.13 billion US$). It is evident that the infiltration from rice paddy is of great importance to the
economy, environment, and water resources conservation in Taiwan. 相似文献
9.
Yumi Iwasaki Masashi Ozaki Kimihito Nakamura Haruhiko Horino Shigeto Kawashima 《Paddy and Water Environment》2013,11(1-4):551-558
There are many paddy fields and large amounts of groundwater in the Tedori River Alluvial Fan in Ishikawa Prefecture, Japan. Water infiltration from paddy fields during irrigation may significantly contribute to groundwater recharge. Groundwater recharge is known to be one outcome of paddy farming, and in general is usually related to land use. However, a decreased area of paddy fields because of socioeconomic factors such as urbanization and increasing area of fallow fields has possibly affected the groundwater environment. Evaluation of the quantitative effect of paddy fields on groundwater is necessary for groundwater conservation. This study examined the relationship between differences in the depth of groundwater from just before the irrigation period to just after the first irrigation of paddy fields (increments of groundwater levels) in observation wells and the area of paddy fields around each well. The paddy areas within circular buffer zones, which were delineated at 0.2 km intervals between 0.2 and 2.0 km centered on each observation well, were calculated. A positive relationship was found between the rise in groundwater and the area of paddy field within different buffer zones at most wells. In addition, in the middle or upper part of the fan, the effect of changes in the area of paddy fields surrounding the well on the groundwater level rise was greater than that on the lower part of the fan. 相似文献
10.
Kenji Tanaka Yoshitaka Funakoshi Takaomi Hokamura Fumihiko Yamada 《Paddy and Water Environment》2010,8(3):217-226
Agricultural fields in the middle Shira River basin play an important role as a source of groundwater recharge; however, the
water balance between the agricultural water and river water is unclear. This study was conducted to investigate the water
balance in the fields by measuring the stream flow of agricultural water channels, which draw water from the Shira River.
The flow rate of water channels was found to increase in the beginning of May, which corresponded to the cultivation of paddy
rice fields. During summer, the total agricultural intake was comparable to the river flow observed in the middle Shira River
Basin. Determination of the water budget for the targeted area revealed that most of the recharged water was dependent on
agricultural irrigation from the river. The annual recharge of the overall target area was estimated to be as high as 15,300 mm.
In addition, the infiltration rate was as high as 170 mm/day in the paddy fields during summer, and as high as 30 mm/day in
the upland fields during winter. In order to recover the groundwater recharge in this region, it is necessary to extend the
submerged period to include periods in which the stream water in the Shira River is not subject to heavy rainfall as well. 相似文献
11.
《Journal of Crop Improvement》2013,27(1-2):353-386
SUMMARY Salinity in soil and water is irrevocably associated with irrigated agriculture throughout the world and as a result requires that salt management becomes an integral part of the production system. With careful water management, it is possible to sustain irrigated agriculture in areas with saline soil and saline groundwater with and without subsurface drainage. The results from two field projects conducted in an area with saline soils and saline groundwater demonstrated the type of irrigation systems and management needed to sustain production of moderately salt tolerant and tolerant crops. During the first study at Murrieta farms, yields of cotton and sugar beet were maintained using both saline and non-saline water for irrigation when pre-plant irrigation and rainfall were adequate to maintain soil salinity at a tolerable level. Wheat production was reduced in areas that used saline water for irrigation. Use of saline water containing toxic elements such as boron for irrigation poses a threat to the sustainability of the system. The second study evaluated the management of furrow and subsurface drip irrigation in the presence of shallow saline groundwater. Careful management of the furrow system during pre-plant irrigation and the first irrigation of the growing season was required to prevent waterlogging. It was possible to manage the subsurface drip system to induce significant crop water use from shallow groundwater. Rainfall and pre-plant irrigation were adequate at this site to manage soil salinity. 相似文献
12.
Shinichi Nishimura Sang-bong Lee Kengo Ito Masateru Senge 《Paddy and Water Environment》2005,3(3):149-154
In the absence of a reservoir on the downstream side, a river flow that increases temporarily by rainfall cannot be stored
and discharged apart from requirements in a command area. This unused water (excess water) occurs to some extent even in a
drought year and making effective use of this supply is considered as one of the countermeasures for water shortage. Setting
up a regulating reservoir on the upstream side of head works is regarded as one of the methods for making effective use of
excess water. The inflow to the river and water delivery loss occurred from rainfall are stored in the regulating reservoir
and supplied to the command area on the downstream side as agricultural water. An operational method for the regulating reservoir
to effectively utilize the excess water was examined for a canal system by simulation. In an investigated area, there was
excess water even in drought years, and making use of it through the regulating reservoir whose capacity is smaller compared
to that of a dam can become one of the countermeasures for the drought period. The simulation in this study could estimate
quantitatively the effect of the regulating reservoir to make the excess water effective. 相似文献
13.
Naoki Kabeya Akira Shimizu Tatsuhiko Nobuhiro Koji Tamai 《Paddy and Water Environment》2008,6(1):25-35
To elucidate the water cycle in lowland forests of the Mekong River basin, our research group established four experimental
watersheds in the Stung Chinit River basin in Kampong Thom Province, Cambodia. The drainage areas of these experimental watersheds
ranged from small (4 km2) to mesoscale (3,659 km2). Here, we present the first preliminary results of our rainfall-discharge observations and analyses of temporal variations
of stable isotope ratios in rainfall, stream water, and groundwater. This paper focuses on the following three main topics:
annual rainfall, discharge, and water balance; stormflow generation and dominant flow pathways; and flow regimes and stream
water residence times. All stream water residence times (τ = 1.7–7.5 months) for the four experimental watersheds were shorter than the residence time of the groundwater (τ = 9.4 months) through the soil and regolith layers, implying that the stream waters consisted of not only the groundwater-flow
component, but also younger-aged flow components such as saturation-excess overland flow. The smallest (4 km2; O Toek Loork) watershed had longer residence time (τ = 7.5 months) than the three larger watersheds (126–3,659 km2; τ = 1.7–3.9 months). This may suggest differing contributions of the groundwater and younger-aged flow components in the stream
water in each watershed. Our approach of multi-scale watershed observation might better contribute to the needs of physically
based models and aid in predictions for ungauged basins. 相似文献
14.
Al-Mashreki MH Akhir JB Abd Rahim S Desa KM Rahman ZA 《Pakistan journal of biological sciences: PJBS》2010,13(23):1116-1128
In the present study, an assessment of land suitability potential for agriculture in the study area of IBB governorate, Republic of Yemen has been conducted through close examination of the indicators of land characteristics and qualities. The objective of this study is to evaluate the available land resource and produce the potential map of the study area. Remote sensing data help in mapping land resources, especially in mountainous areas where accessibility is limited. Satellite imagery data used for this study includes data from multi-temporal Landsat TM which dated June 2001. The parameters taken into consideration were 16 thematic maps i.e., slope, DEM, rainfall, soil, land use, land degradation as well as land characteristics maps. Satellite image of the study area has been classified for land use, land degradation and soil maps preparation, while topo sheet and ancillary data have been used for slope and DEM maps and soil properties determination. The land potential of the study area was categorized as very high, high, moderate, low and very low by adopting the logical criteria. These categories were arrived at by integrating the various layers with corresponding weights in a Geographical Information System (GIS). The study demonstrates that the study area can be categorized into spatially distributed agriculture potential zones based on the soil properties, terrain characteristics and analyzing present land use. This approach has the potential as a useful tool for guiding policy decision on sustainable land resource management. 相似文献
15.
为了恢复干热河谷退化山区草地的生态环境,提高草地的水土保持能力,于2004～2007年在金沙江干热河谷区的云南省永胜县设置样点,在退化严重的草地上建植了7个组合模式的灌草复合型草地,以凋落物量、最大持水量、有效截流量、草地盖度、草地土壤崩解时间为指标,对建植3年的灌草草地的水保效果进行研究。结果表明,＂灌＋草＋藤＂最适宜金沙江干热河谷区的植被重建,其中＂木豆＋非洲狗尾草＋高羊茅＋大翼豆＂建植模式显著地提高草地植被盖度和凋落物重量。凋落物的持水能力与凋落物重量呈显著的正相关;土壤根量与土体崩塌时间呈显著的正相关。灌草草地植被盖度、凋落物量和根系重量的显著提高,有效地提高草地的持水量和有效截流量,推迟草地土壤崩解时间,增加了土体的稳定性,对防止水土流失和泥石流的形成具有重要作用。 相似文献
16.
17.
In this study, the clustering method was applied to improve the usage of effective rainfall (ER) for irrigating rice paddy in the region managed by the TaoYuan Irrigation Association (TIA) of Taiwan. A total of 16 rainfall stations and rainfall data from 1981 to 2000 were used. A traditional area-weighted method (Thiessen polygons method) and an optimal clustering model of ER were evaluated and compared. The optimal clustering model of ER comprised self-organizing map (SOM), k-means (KM), and fuzzy c-means (FCM) clustering algorithms. To obtain optimal clustering data of ER, the clustering groups from two to five of SOM, KM, and FCM algorithms were determined using root-mean-squared-error. The results show that three algorithms with group numbers from two to five are adopted for the monthly optimal clustering model in different months. However, for the annual optimal model, 12 sub-models are assessed and then compared. The results show that the SOM clustering with groups three was the optimal model for annual ER. The optimal clustering model of ER provides a new procedure step in preparation of the irrigation scheduling for the TIA, and the amount irrigation water waste can be reduced from 770.1 to 22.3 mm/year. The planned ER using the optimal clustering model significantly improves the irrigation water use efficient in agricultural water management. 相似文献
18.
Reciprocal influence of crops and shallow ground water in sandy landscapes of the Inland Pampas 总被引：1，自引：0，他引：1
In regions with shallow water tables, ground water may have a positive (water supply) or negative (waterlogging or salinization) impact on crops. Reciprocally, crops can influence ground water, altering water table depth and chemical composition. We quantified these reciprocal influences along natural gradients of groundwater depth in flat sedimentary landscapes of the Inland Pampas occupied by wheat, soybean, and maize during two growing seasons (2006/2007 and 2007/2008). We correlated crop yield and groundwater depth maps at the field level and made direct plant, soil and groundwater observations at the stand level across topographic gradients. Water table level largely accounted for spatial crop yield variation, explaining 20–75% of their variance. An optimum groundwater depth range, where crop yields were highest, was observed for all three crop species analyzed (1.40–2.45 m for maize, 1.20–2.20 m for soybean, and 0.70–1.65 m for wheat). The areas within these optimum bands had yields that were 3.7, 3 and 1.8 times larger than those where the water table was below 4 m for wheat, maize, and soybean, respectively. As groundwater levels become shallower than these depth bands, crop yields declined sharply (∼0.05 kg m−2 on average for every 10 cm increase in water table level), suggesting negative effects of waterlogging, root anoxia and/or salinity. Groundwater levels below these depth bands were associated with gradually declining yields, likely driven by poorer groundwater supply. 相似文献
19.
The water balance and groundwater dynamics due to surface–groundwater interactions for watershed health assessment were investigated for the Han River basin (34,148 km2) of South Korea using the Soil and Water Assessment Tool (SWAT). The model was established considering 4 multipurpose dams and 3 multifunction weirs. The SWAT was spatially calibrated and validated using daily observed inflows for the dam (2005–2014) and weir (2012–2014) as well as evapotranspiration, soil moisture, and groundwater level data (2009–2013). The simulation results revealed the impact of surface–groundwater exchange fluxes on the water balance and baseflow by evaluating the vertical water budget and horizontal water transfer. Evapotranspiration in the surface and return flows from the shallow aquifer for the dry season was estimated to be 29 and 10% higher than for the wet season, respectively. Percolation’s role was also significant, providing approximately 24% of the annual groundwater recharge to shallow aquifers in the rainy season. On average, the February to August period (A) was characterized by a net flux of infiltration into the groundwater. For the September to January period (B), the proportion of groundwater flow into the river of the basin was nearly balanced by a slight increase in surface water infiltration. During period A of average surface water infiltration into the groundwater, the net groundwater recharge was positive and up to 20% of the infiltration during this period resulted from groundwater recharge. These results showed that groundwater recharge is strongly affected by the surface water and groundwater interactions. 相似文献
20.
Ya-Wen Chiueh 《Paddy and Water Environment》2012,10(1):41-47
In this study, the demand function for the transferring agricultural water to industrial water during non-drought period covering
from January 1998 to December 2008 in Taiwan was estimated, and the water usage statistics derived from the short-term water
charge agreements, regarding the charging of water management fees and water usage fees from the irrigation associations,
were applied to the estimation in the empirical model. The results of the research are presented as follows: (a) the demand
for transferring agricultural water into industrial water is non-elastic; the price elasticity is −0.368; (b) the transferred
water volume decreases when the water price rises; (c) the transferred water volume also decreases when the wholesale price
index of domestic products rises; (d) the buyer’s industry classification was the significant factor influencing the transfer
water demand; (e) the different title of transferred water including: “building utilization cost” or that in “costs for enhanced
irrigation management” was the significant factor influencing the transfer water demand; (f) type of repository of irrigation
association for transferred water was the significant factor influencing the transfer water demand; (g) whether irrigation
association enhances irrigation management was the significant factor influencing the transfer water demand; (h) the source
of transferred water was the significant factor influencing the transfer water demand; (i) the method for water transfer was
the significant factor influencing the transfer water demand; (j) more water transferred by the industry when the total population
of Taiwan increases; (k) the transferred water volume rises when the groundwater level of the water transferred area rises;
and (l) the areas for water transferred was the significant factor influencing the transfer water demand. 相似文献