호남평야지에서 보리 후작 벼 담수표면직파재배시 파종 한계기를 설정하기 위하여 1998~1999 년에 호남농업시험장 수도포장인 전북통(미사질양토)에서 조생종 삼천벼, 상주벼, 오봉벼, 중생종 금오벼 1호, 주안벼를 공시하여 6월 5일, 6월 10일, 6월 15일, 6월 20일에 10 a당 7 kg씩 담수표면산파하여 생육 및 쌀 수량 등을 검토한 결과를 요약하면 다음과 같다. 1. 입모율은 68~81% 로 파종시기가 빠를수록 입모율이 다소 높은 경향이었다. 2. 도복은 오봉벼, 주안벼에서 경미하게 발생하였으나 삼천벼, 상미벼, 금호벼 1호는 도복발생이 심했다. 3. 안전출수기로 본 파종한계기는 삼천벼, 상주벼, 오봉벼의 경우 6월 20일까지, 금오벼 1호와 주안벼는 6월 15일까지였다. 4. 쌀 수량은 6월 5일 파종과 6월 10일 파종은 파종기간에 별 차이가 없었으나 6월 15일 이후 파종에서는 수량감소가 컸다. 5. 따라서 호남평야지에서 보리 후작 벼 담수표면직파재배시 출수기, 수량 등을 고려한 파종한계기는 6월 10일이었다.

This study utilized the 1/25,000 topographic map of the upper area from the Geum-ho watermark located at the middle of Geum-ho river from the National Geographic Information Institute. For the analysis, first, the influence of the size of critical area to the hydro topographic factors was examined changing grid size to 10m×10m, 30m×30m and 50m×50m, and the critical area for the formation of a river to 0.01㎢∼0.50㎢. It is known from the examination result of watershed morphology according to the grid size that the smaller grid size, the better resolution and accuracy. And it is found, from the analysis result of the degree of the river according to the minimum critical area for each grid size, that the grid size does not affect on the degree of the river, and the number of rivers with 2nd and higher degree does not show remarkable difference while there is big difference in the number of 1st degree rivers. From the results above, it is thought that the critical area of 0.15㎢∼0.20㎢ is appropriate for formation of a river being irrelevant to the grid size in extraction of hydro topographic parameters that are used in the runoff analysis model using topographic maps. Therefore, the GIUH model applied analysis results by use of the river level difference law proposed in this study for the explanation on the outflow response-changing characters according to the decision of a critical value of a minimum level difference river, showed that, since an ogival occurrence time and an ogival flow volume are very significant in a flood occurrence in case of not undertow facilities, the researcher could obtain a good result for the forecast of river outflow when considering a convenient application of the model and an easy acquisition of data, so it's judged that this model is proper as an algorism for the decision of a critical value of a river basin.