Neraca air MSP GFM

Public Sub neraca_air()
        'Intersepsi Tajuk Tanaman :
        If lai(i) < 3 Then
            ic(i) = 0.4233 * lai(i)
        Else
            ic(i) = 1.27
        End If

        If ch(i) < ic(i) Then ic(i) = ch(i)

        'Curah Hujan Effektif/netto
        ch_ef(i) = ch(i) - ic(i)

        'Run off fungsi kemiringan dan CHeff:
        ro(i) = Math.Sin(3.14 * miring / 180) * ch_ef(i)

        'Evapotranspirasi (Penman):
        f1 = 0.64 * (1.054 * angin(i))
        del = 208.84
        ETP(i) = (del * 0.5 * rad(i) + f1 * (100 - rh(i)) / 100 * 2000) / (del * 66.1)

        'Evaporasi (Ea) dan Transpirasi (Ta):
        Em(i) = ETP(i) * Math.Exp(-0.5 * lai(i))
        Tm(i) = ETP(i) - Em(i)

        If KAT(i - 1) < KL Then
            If KAT(i - 1) > TLP Then Ta(i) = Tm(i) * (KAT(i - 1) - TLP) / (KL - TLP) Else Ta(i) = 0
        Else
            Ta(i) = Tm(i)
        End If
        If KAT(i - 1) < (TLP / 2) Then Ea(i) = 0 Else Ea(i) = Em(i)

        'Kadar Air Tanah (mm) :
        KAT(i) = KAT(i - 1) + ch_ef(i) - ro(i) - Ea(i) - Ta(i)

        'Perkolasi :
        If KAT(i) > KL Then
            Pc(i) = KAT(i) - KL
            KAT(i) = KL
        Else
            Pc(i) = 0
        End If
        If KAT(i) < 0 Then KAT(i) = 0

        'water defisit factor
        wdf(i) = Ta(i) / Tm(i)

    End Sub