Sensitivity analysis of a three-dimensional subsurface irrigation hydrology model

Year 2011, Volume: 24 Issue: 1, 25 - 32, 01.06.2011

D. Buyuktas W. W. Wallender

Abstract

In this study, a sensitivity analysis was performed and presented for a three-dimensional subsurface irrigation hydrology model. Input parameters such as number of nodes, van Genuchten’s soil hydraulic parameters (Ks, α, and n), the longitudinal and transverse dispersivity (αL, αT), the sorption distribution coefficient (Kd), initial solute concentration distribution, water table depth from soil surface and root water uptake parameters were changed by fixed amounts around a base value and the resulting changes in the outputs were analyzed. Results showed that output was sensitive to van Genuchten’s soil hydraulic parameters (Ks, α, and n), initial solute concentration distribution, water table depth and root water uptake parameters. The cumulative solute load was insensitive to the changes in the αL, and Kd, while the solute concentration distribution was quite sensitive to these parameters. The simulated outputs were not sensitive to the changes in the number of nodes and transverse dispersivity coefficient. Results could be used by modelers not only for this model but also for similar models.

Keywords

Duyarlılık analizi, Sayısal modelleme, Toprakaltı hidrolojisi

Üç boyutlu bir toprakaltı sulama hidrolojisi modelinin duyarlılık analizi

Abstract

Bu çalışmada, üç boyutlu bir toprakaltı sulama modelinin duyarlılık analizi yapılarak sonuçları sunulmuştur. Düğüm sayısı, van Genuchten toprak hidrolik parametreleri (Ks, α, ve n), boyuna ve enine dispersivite (αL, αT), soğurma dağılım katsayısı (Kd), başlangıç çözünmüş madde konsantrasyonu, su tablası derinliği ve kök su alım parametreleri gibi modelin giriş parametreleri bir baz değere göre belirli oranlarda değiştirilmiş ve bu değişikliğe bağlı olarak elde edilen sonuçlar analiz edilmiştir. Model sonuçlarının van Genuchten toprak hidrolik parametreleri, başlangıç çözünmüş madde konsantrasyonu, su tablası derinliği ve kök su alım parametrelerine karşı duyarlı olduğu belirlenmiştir. Kümülatif çözünmüş madde yükünün αL, ve Kd’deki değişikliklere duyarsız olduğu gözlenirken, toprak profilindeki çözünmüş madde konsantrasyonu dağılımının söz konusu parametrelere karşı duyarlı olduğu gözlenmiştir. Simülasyon sonuçlarının düğüm sayısı ve enine dispersiviteye karşı duyarsız olduğu belirlenmiştir. Sonuçlar, sadece bu model için değil buna benzer model çalışmalarında da kullanıcılar için yararlı olacaktır

Keywords

Duyarlılık analizi, Sayısal modelleme, Toprakaltı hidrolojisi

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