Crop planting structure extraction in irrigated areas from multi-sensor and multi-temporal remote sensing data. In Chinese

Crop planting structure extraction in irrigated areas includes a range of dynamic parameters which require proper spatial and temporal resolution remotely sensed data. The paper seeks to extract crop planting structure by employing multi-temporal images from multi-sensors. Landsat enhanced thematic mapper plus (ETM+) images and moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) monthly data were res-merged to produce a mega data tube, which was then classified using ISO cluster algorithm. Spectral signature of each class was extracted and identified using spectral matching technique taking crop coefficient curve as reference. In the way Zhanghe Irrigation system in southern China was classified into four classes: rice-rapeseed rotation, rice-wheat rotation, single summer crops, and double economic crops. Accuracy assessment suggests good agreement with statistical data and 91% classification accuracy when using IKONOS high resolution images as Ground Truth data. The application demonstrates the method a cost-efficient and robust approach to extract crop planting structure at irrigation system scale

Estimating pond storage capacity using remote sensing and GIS: A case study in Zhanghe irrigation scheme, southern China

In Proceedings of the 2nd International Symposium on Methodology in Hydrology, held in Nanjing, China, October - November, 2005. IAHS Publication 311, 2007There are numerous ponds in Southern China and it is very difficult to evaluate their contribution to local water users because of their small size and wide variance. This paper presents two methods for estimating pond storage capacity using RS/GIS. One is to estimate pond storage capacity as a function of the topographic factors. An indicator, PV, pond storage capacity per unit rice area of 86 villages, is calculated, and then the correlation between PV, slope, altitude and drainage density is calculated to estimate the pond storage capacity of whole study area. The other method is to extrapolate estimated results from a high resolution image of small scale to a low resolution image of large scale area. With field information and IKONOS image (1 m), the pond storage of a small scale area is estimated using a pond surface area-volume function, and then the value is extrapolated to large scale area with reference to a LandSat ETM image (14.25 m). The two methods are applied to Zhanghe irrigation district, and the application results show that the results are acceptable

Adapting to intersectoral transfers in the Zhanghe Irrigation System, China: Part I - In-system storage characteristics

The Zhanghe Irrigation System (ZIS), in Central China, has drawn attention internationally because it managed to sustain its rice production in the face of a dramatic reallocation of water to cities, industries and hydropower uses. Ponds, the small reservoirs ubiquitous in the area, are hypothesized to have been instrumental in this. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. They provide a flexible, local source of irrigation water to farmers. This paper assesses the storage capacity and some key hydrological properties of ponds in a major canal command within ZIS. Using remote sensing data (Landsat and IKONOS) and an area-volume relationship based on a field survey, we obtained an overall pond storage capacity of 96 mm (per unit irrigated area). A comparative analysis between 1978 and 2001reveals that part of this capacity results from a very significant development of ponds (particularly in the smaller range of sizes) in the time interval, probably as a response to rapidly declining canal supplies. We developed a high-resolution digital elevation model from 1:10,000 topographic maps to support a GIS-based hydrological analysis. Pond catchments were delineated and found to extensively overlap, forming hydrological cascades of up to 15 units. In a 76-km2 area within the irrigation system, we found an average of close to five 'connected' ponds downstream of each irrigated pixel. This high level of connectivity provides opportunities for multiple reuses of water as it flows along toposequences. A fundamental implication is that field 'losses' such as seepage and percolation do not necessarily represent losses at a larger scale. Such scale effects need to be adequately taken into account to avoid making wrong assumptions about water-saving interventions in irrigation

Spatio-temporal Analysis in Land Use Change and Its Application in Lijiang Region

Land Use / Cover Change (LUCC) is an essential component in the field of regional environmental monitoring and economic development analysis. Its motivation is to get an indepth understanding of dynamic process, leading causes and evolution mechanism of regional land use change, which provide accurate information for land administration to develop local economic development planning and management. Data analysis and processing plays a key role in LUCC. This paper summarizes four kinds of spatio-temporal analysis indexes, including magnitude, velocity, regional differences and inner conversion. Then Lijiang Region is taken as an example, and these four indexes are applied to analyze its land use change. Results reveal numerical and spatial difference in LUCC, and they are accorded with local actual conditions. ? 2010 IEEE.EI

Local storages: the impact on hydrology and implications for policy making in irrigation systems

OASIS, an irrigation diagnosis model, is applied to the Zhanghe Irrigation System in central China to investigate the contribution of smaller local storages (in �melons on the vine� configuration) as compared with the main reservoir. Results show that local storages are more important in normal-to-wet years, while the main reservoir is critical in dry years, which implies a strong policy correction relevant to many parts of the world. Balanced investment in various storage infrastructures with associated management practices is a cost-effective strategy for irrigation development

Mapping Paddy Rice Distribution and Cropping Intensity in China from 2014 to 2019 with Landsat Images, Effective Flood Signals, and Google Earth Engine

Paddy rice cropping systems play a vital role in food security, water use, gas emission estimates, and grain yield prediction. Due to alterations in the labor structure and the high cost of paddy rice planting, the paddy rice cropping systems (single or double paddy rice) have drastically changed in China in recent years; many double-cropping paddy rice fields have been converted to single-cropping paddy rice or other crops, especially in southern China. Few maps detect single and double paddy rice and cropping intensity for paddy rice (CIPR) in China with a 30 m resolution. The Landsat-based and effective flooding signal-based phenology (EFSP) method, which distinguishes CIPR with the frequency of the effective flooding signal (EFe), was proposed and tested in China. The cloud/ice/shadow was excluded by bit arithmetic, generating a good observation map, and several non-paddy rice masks were established to improve the classification accuracy. Threshold values for single and double paddy rice were calculated through the mapped data and agricultural census data. Image processing (more than 684,000 scenes) and algorithm implementation were accomplished by a cloud computing approach with the Google Earth Engine (GEE) platform. The resultant maps of paddy rice from 2014 to 2019 were evaluated with data from statistical yearbooks and high-resolution images, with producer (user) accuracy and kappa coefficients ranging from 0.92 to 0.96 (0.76–0.87) and 0.67–0.80, respectively. Additionally, the determination coefficients for mapped and statistical data were higher than 0.88 from 2014 to 2019. Maps derived from EFSP illustrate that the single and double paddy rice systems are mainly concentrated in the Cfa (warm, fully humid, and hot summer, 49% vs. 56%) climate zone in China and show a slightly decreasing trend. The trend of double paddy rice is more pronounced than that of single paddy rice due to the high cost and shortages of rural household labor. However, single paddy rice fields expanded in Dwa (cold, dry winter, and hot summer, 11%) and Dwb (cold, dry winter, and warm summer, 9%) climate zones. The regional cropping intensity for paddy rice coincides with the paddy rice planting area but shows a significant decrease in south China, especially in Hunan Province, from 2014 to 2019. The results demonstrate that EFSP can effectively support the mapping of single and double paddy rice fields and CIPR in China, and the combinations of Landsat 7 and 8 provide enough good observations for EFSP to monitor paddy rice agriculture

Experimental Study on Wetland Hydraulic Characteristics of Vegetated Drainage Ditches

Small vegetated drainage ditches play an important role in water and nutrient removal, but may cause water blocking problems. The aim of this study was to investigate vegetated drainage ditches’ hydraulic and wetland hydraulic characters. Field experiment were carried out, small drainage ditches with Juncus, Zizania latifolia, and Acorus calamus were selected under different water flows, and a tracer experiment was also conducted. Research findings suggested that with increased water flow, vegetation roughness coefficient declined, vegetation resistance rose, and drag coefficient declined. Small drainage ditches with emergent vegetation showed a high roughness coefficient value, which was most significant in Juncus, followed by Zizania latifolia, and Acorus calamus. Plants each took on a unique eigenvalue k that was a relative coefficient between the drag coefficient and stem Reynolds number. As small ditches for drainage showed longer residence time and smaller surface hydraulic loading, they featured excellent wetland hydraulic characteristics that could be weakened rapidly as rainfall or flood intensified. This study indicates that the small vegetated drainage ditch shows favorable wetland hydraulic characteristics with good discharge capacity and can be extensively used in irrigated districts

Mapping Paddy Rice Distribution and Cropping Intensity in China from 2014 to 2019 with Landsat Images, Effective Flood Signals, and Google Earth Engine

Paddy rice cropping systems play a vital role in food security, water use, gas emission estimates, and grain yield prediction. Due to alterations in the labor structure and the high cost of paddy rice planting, the paddy rice cropping systems (single or double paddy rice) have drastically changed in China in recent years; many double-cropping paddy rice fields have been converted to single-cropping paddy rice or other crops, especially in southern China. Few maps detect single and double paddy rice and cropping intensity for paddy rice (CIPR) in China with a 30 m resolution. The Landsat-based and effective flooding signal-based phenology (EFSP) method, which distinguishes CIPR with the frequency of the effective flooding signal (EFe), was proposed and tested in China. The cloud/ice/shadow was excluded by bit arithmetic, generating a good observation map, and several non-paddy rice masks were established to improve the classification accuracy. Threshold values for single and double paddy rice were calculated through the mapped data and agricultural census data. Image processing (more than 684,000 scenes) and algorithm implementation were accomplished by a cloud computing approach with the Google Earth Engine (GEE) platform. The resultant maps of paddy rice from 2014 to 2019 were evaluated with data from statistical yearbooks and high-resolution images, with producer (user) accuracy and kappa coefficients ranging from 0.92 to 0.96 (0.76–0.87) and 0.67–0.80, respectively. Additionally, the determination coefficients for mapped and statistical data were higher than 0.88 from 2014 to 2019. Maps derived from EFSP illustrate that the single and double paddy rice systems are mainly concentrated in the Cfa (warm, fully humid, and hot summer, 49% vs. 56%) climate zone in China and show a slightly decreasing trend. The trend of double paddy rice is more pronounced than that of single paddy rice due to the high cost and shortages of rural household labor. However, single paddy rice fields expanded in Dwa (cold, dry winter, and hot summer, 11%) and Dwb (cold, dry winter, and warm summer, 9%) climate zones. The regional cropping intensity for paddy rice coincides with the paddy rice planting area but shows a significant decrease in south China, especially in Hunan Province, from 2014 to 2019. The results demonstrate that EFSP can effectively support the mapping of single and double paddy rice fields and CIPR in China, and the combinations of Landsat 7 and 8 provide enough good observations for EFSP to monitor paddy rice agriculture