灌溉發展的方案策略-以馬拉威的亞熱帶環境為例

Scenario Based Strategies for Irrigation Development under Semiarid Environment of Malawi

那威力(Willy Namaona)

指導教授 ： 王裕民 博士

國立屏東科技大學/農學院/熱帶農業暨國際合作系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00053

摘要

全世界人口逐漸成長，相對也必須提高糧食產量，以因應增加的需求量。全球主要面對的挑戰是加強水生產力，當土地有限時，每單位作物收成量也必須提高。鑑此，吾人可得二個基本的發展方向：對於目前作物收成量趨於潛力收成量的地區，仍提高其產量；對於利用現代技術可提高大量生產的地區，來減少作物收成差。基於上述假設，本文選擇在非洲地區馬拉威，搜集在不同地區的氣象與作物資料進行灌溉發展之研究。首先為考量提升水生產力，依據FAO Penman Monteith (FPM)模式，在不同地區建立季節性氣象資料來推測參考蒸發散量。此外，若缺少單一氣象資料如風速、相對溼度或日照期，以FPM取得估算值作為蒸發散量計算是為可行亦在研究中被証實。本研究檢視在布吉納法索Ouagadougou地區及馬拉威Ngabu地區，其合宜耕作期時的雨水灌溉之作物需水量。利用降雨量指數和作物收成量來觀察雨水是否足以滿足作物需水量，進而預估收成量。研究結果顯示，於合宜耕作期間，玉蜀黍、豆類、小米及花生的收成量在Ouagadougou可增加10.31、16.22、10.57、4.82%，而在Ngabu可增加5.00、7.41、7.14、4.30%。本研究也探討在Chileka利用太陽能幫浦灌溉的可行性，分析0.5Hp幫浦運用灌溉豆類、玉蜀黍、與蕃茄。以此系統和雨水灌溉作物收成差作為效益的基礎，結果顯示，PVP系統所產生的能源足以提供Chileka地區灌溉用水，但該系統用於灌溉蕃茄有較佳的效益。透過馬拉威政府的永續灌溉農業政策，極力推薦在Chileka運用PVP系統灌溉蕃茄來促進社會經濟發展。另一項研究是在屏東科技大學實驗地的土壤水份監測，並以該土壤條件運用馬拉威的氣象資料來決定灌溉期距。所以，本論文針對農業生產提供不同的策略便能有效率並永續的水資源及土地利用。

關鍵字

灌溉 ； 農業水 ； 溫度基礎的模式 ； 太陽能 ； 作物產量 ； 土壤水份

並列摘要

As the world population continues to grow, so does the need to constantly increases food production. Several actions are required to cope with this increasing demand. Globally, the core challenge must be to improve water productivity. Where land is limiting, yields per unit area must also be enhanced. These measures lead to two basic development directions; increasing the yield in areas where present levels of production are close to their potential; closing the yield gap where considerable production gains can be achieved with current technologies. Based on the above scenarios, studies were carried out to develop irrigation agriculture in Malawi. The studies were done based on climatic data and crop information collected from different areas of Malawi. By considering the fact of improving water productivity, seasonal temperature-based method of estimating reference evapotranspiration based on FAO Penman Monteith (FPM) equation was established for different study sites. Furthermore it has been confirmed that when a single climatic variable such as wind speed, relative humidity or sunshine duration is missing, its estimated value from the FPM missing data procedure can be used for accurate ETo computation in Malawi. The thesis also, examines the scope for meeting the crop water demand under rainfed condition based on the suitable planting period approach in Ouagadougou of Burkina Faso and Ngabu of Malawi. The rainfall contribution index and yield estimation model were introduced to examine the availability of rainwater to suffice the crop water demand and then predicting the yields. Following the suitable planting periods determined in this study might increase the yield of maize, bean, millet, and groundnuts by 10.31, 16.22, 10.57, and 4.82 % in Ouagadougou, and 5.00, 7.41, 7.14, and 4.30 % in Ngabu, respectively. This paper also presents the results of feasibility analysis of using solar powered pump for irrigation in Chileka. The 0.5Hp pump was analyzed if it can be used for irrigation of beans, maize and tomato. The system was compared with rainfed production by taking the yield gap as the gain from the system. The results show that, the energy is enough for the studied PVP system for irrigation in Chileka. However, based on the economic analysis, the system is only viable for irrigation of tomato. The use of the PVP system is therefore strongly recommended for irrigation of tomato in Chileka to promote social and economic development through sustainable irrigated agriculture which is the overall Malawi government’s policy. Another study was done on soil moisture monitoring using results of soil tests from National Pingtung University of Science and Technology experimental field. The soil information was linked with the climatic condition of Malawi to determine irrigation interval by assuming similar soil condition in the study sites. The soil was determined to be clay loam and monthly constants for each site were obtained and recommended for monitoring soil moisture and determination of irrigation interval. Therefore, strategies based on different scenarios presented in this thesis are recommended to ensure the efficient and sustainable use of water and land for agricultural production.

並列關鍵字

irrigation ； agricultural water ； temperature based models ； photovoltaic ； crop productivity ； soil moisture

參考文獻

Action Aid. 2006. Climate change and smallholder farmers in Malawi.. http://www.actionaid.org.uk/doc_lib/malawi_climate_change_report.pdf.

Alexandris, S., P. Kerkides, A. Liakatas. 2006. Daily reference evapotranspiration estimates by the “Copais” approach. Agriculture Water Management, 82: 371-386.

Bois, P., C. Pieri, L. Van leeuwen, F. Wald, J. Huard, P. Gaudillere, and E. Saur. 2008. Using remotely sensed solar radiation data for reference evapotranspiration estimation at a daily time step. Agriculture and forest meteorology, 148:619-630

Boling, A. A., B. A. M. Bouman, T. P. Tuong, M. V. R. Murty and S.Y. Jatmiko. 2007. Modelling the effect of groundwater depth on yield-increasing interventions in rainfed lowland rice in Central Java, Indonesia. Agricultural Systems, 92: 115-139.

Braga, R. P., M. J. Cardoso and J. P. Coelho. 2008. Crop model based decision support for maize (Zea mays L.) silage production in Portugal. European Journal of Agronomy, 28: 224-233.