There is no denying the fact that all international rivers like the Nile, the Rhyne, the Mekong the Ganges and the like are the heritage of mankind. But the Ganges which flows through upper riparian Nepal, India and lower ripparian Bangladesh, has its peculiarity that its monsoon flow (June-November) is sufficient to meet the needs of India and Bangladesh, but its dry season flow (January-May) is insufficient Recently India and Bangladesh have undertaken their own development plans for which the countries need to share the amount of available dry season flow. This has obviously resulted in a conflict of national interest. And the dispute has been aggravated due to construction of a structure called Farakka Barrage to divert the Ganges dry sea-son flow into the Bhagirthi-Hoogly river to improve the navigability of the Calcutta Port of West Bengal, India. The Ganges dispute had its genesis in the partition of India in 1947. The division split the river system both in the western and eastern sectors. As the two independent states (India and Pakistan) began to formulate their own plans for the development of waters of the rivers lying within their territories, dispute over these water surfaced both east and west. The entire period of negotiations over the Ganges water may be divided into six phases viz. (a) 1951 to 1971 i.e. the Pakistan phase. (b) 1972 to 75 i.e. early Bangladesh phase (c) 1975-1981 (d) 1982 to 1988 (e) 1988 to 1995 and (f) 1995 to 1996 i.e., the final phase of 30 years agreement. The Pakistan phase was marked by a feeling of hostility and distrust. Early Bangladesh phase had discussion on equitable allocation of Ganges water before commissioning of the Farakka Barrage. The phase 1975 to 81 is the break through in the form of 5 year Agreement in government level on April 18, 1977. Phase 1982 to 1988 was the extension of 5 year Agreement through a temporary Memorandum of Understanding (MOU). Phase 1988 to 1995 was the period without any agreement. Finally a 30 year water agreement was signed on December 12, 1996 between the two governments. It is ex-pected that Bangladesh will receive its due share of water as per the terms of reference of this new 30 year agreement. This new 30-year agreement is mainly based on the availability of the Ganges water at Farakka point. Since the average water flow at Farakka depends on natural factors as well as the withdrawal of water in Uttar Pradesh and Bihar states of India. so there is always a chance phenomenon that Bangladesh may not get its due share if less flow reaches at Farakka point as there is no guarantee clause for assured water quantum in this new 30-year Agreement.

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植生地における熱収支項,地表面温度,土壌水分の日変化および季節変化を計算する植生モデルを示した.モデルは植生を1層,土壌を2層として取り扱っている.計算に必要な気象データは日降水量,日最高・最低気温,日照時間,日平均風速,日平均水蒸気圧,日平均気温である.モデルの計算結果はタヌキ豆圃場における観測値をほぼ再現することができた. 土壌水分が観測されていないことを想定し,リモートセンシングによって算定,される活性度指数を用いて潜熱に対する葉面輸送係数と土壌水分を推定する方法を提案した.

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地表面の熱収支・水収支にとって重要な要素である積雪と植生について,分光反射特性を調べ,その特徴を用いて植生密度の分類や積雪のあるなしといったことの判別法を検討した.分光反射特性の測定は,とくに高緯度地域における積雪のある森林域を念頭におき,可搬のポット苗を用いることで植生密度や林床の積雪の有無などの条件を変えて行った.複数の要素が混在する地表面の分光反射特性を再現できる簡便なモデルを検討し,正確な再現には林内の多重散乱を考慮する必要があることがわかった.次に以上の結果を応用することで,リモートセンシングにより植生の状態を知るための植生指標と積雪の有無を判別できる積雪指標を提案した.これまでの代表的な植生指標は,可視・近赤外波長域のそれぞれについて1波長帯を使い,植生の活性度などを見積もる指標であったが,林床の地表面の影響が無視できない場合,土壌の種類により同じ植生でも指標が異なり,とくに地表面が積雪の場合には誤って植生を見積もってしまっていた.今回提案する可視1波長帯・近赤外2波長帯域で計3波長帯の測定値を使用する植生指標では,葉面積指数LAIが3m2m-2未満の植生について,土壌の種類や積雪などの地表面要素によらずLAIのみで決まることから,植生密度を判定できることを確かめた.また,積雪指標でも同様にLAIが3m2m-2未満の植生について,林床の積雪の有無が判別できるという結果を得た.

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大河川流域を対象とした流出シミュレーションシステムを構築する.このシステムは,気象予測モデルによって計算される水文量を入力とすることを想定し,各グリッドボックスからの流出量を実河道網に即して追跡して流域多地点での流量ハイドログラフを算定する.このモデルをタイ国チャオプラヤ川流域に適用し本システムの性能を検証する.

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