| In this paper, based on stratified sampling method, selected 5 irrigation sub-districts and used canal dynamic water method to determine flows. Then, it studied canal-system water use efficiency from motion aspect to static aspect. According to measured data, it calculated the typical canal water use efficiency. It also studied multiple factors on canals. Based on colleted data in Hetao irrigation district, it calculated fractal dimension and analyzed the relationship between fractal dimension and canal-system water use efficiency. The main conclusions were:1. Canals were influenced by many factors, such as length, control area and flow. Based on principle component analysis, it got natural factor and water-saving engineering factor.Natural factor determined scale of canal and water-saving engineering factor determined canal water use efficiency. Bases on this, it sorted scores of canals and made a conclusion that we should line the upstream canal.For proving a model concluded many factors, multiple regressed was used.2. The relation between unit canal length water loss rates and flows were exponential relationship. Each canal had its own best flow range. Canal water use efficiency in upstream was bigger than it in downstream.3. According to canal water use efficiency in different sub-districts, it calculated canal-system water use efficiency. Based on modified continued multiplication, canal-system water use efficiency was 48%. Based on sub-districts area weighted method, canal-system water use efficiency was 47.77%. These 2 results were very close.4. According to Yangjiahe main canal, it got a lining model.From this, it forecasted that canal-system water use efficiency could reach 62.59% after total lining. The water saving rates could reach 28.06%.5. According to data in Hetao irrigation district, it got fractal dimension of canal-system. The branch ratio, length ratio and fractal dimension were in rational range. This showed that canal-system structure was accord with Horton law.If fractal dimension was too high, canal-system structure would be redundant. If fractal dimension was too low, canal-system structure would be too simple. So, it got a model concluded fractal dimension and canal-system water use efficiency.6. If enhancing canal-system water use efficiency, we should study lining and canal-system. Finally, it proposed the evaluation model and the water saving potential model. |
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