SUBROUTINE FRUNOFF (NPNTS,R,TFALL,CAN_WCNT,CAN_CPY,INFIL,AREA 7APA1F405.128
&, RUNOFF,TIMESTEP) APA1F405.129
APA1F405.130
IMPLICIT NONE FRUNOF1A.32
! APA1F405.131
! Description: APA1F405.132
! Calculates the fast (surface) runoff at the soil surface APA1F405.133
! APA1F405.134
! Documentation: APA1F405.135
! APA1F405.136
! Current Code Owner: Peter Cox APA1F405.137
! APA1F405.138
! History: APA1F405.139
! Version Date Comment APA1F405.140
! ------- ---- ------- APA1F405.141
! 4.5 6/98 Options to interpret canopy moisture as bimodally APA1F405.142
! rather than uniformily distributed, with either a APA1F405.143
! random or maximum overlap of the wet canopy and APA1F405.144
! the precipitating area (P.M.Cox) APA1F405.145
! 4.5 01/10/98 Removed old section-version defs. K Rogers APA1F405.146
! APA1F405.147
! Code Description: APA1F405.148
! Language: FORTRAN 77 + common extensions. APA1F405.149
! APA1F405.150
! System component covered: P25 APA1F405.151
! System Task: P25 APA1F405.152
! APA1F405.153
! Subroutine arguments APA1F405.154
! Scalar arguments with intent(IN): APA1F405.155
INTEGER APA1F405.156
& NPNTS ! IN Number of gridpoints. APA1F405.157
APA1F405.158
REAL APA1F405.159
& TIMESTEP ! IN Model timestep (s). APA1F405.160
&,AREA ! IN Fractional area of the gridbox over APA1F405.161
C ! which water falls. APA1F405.162
APA1F405.163
! Array arguments with intent(IN): APA1F405.164
REAL APA1F405.165
& R(NPNTS) ! IN Flux of water incident on the APA1F405.166
C ! canopy (kg/m2/s). APA1F405.167
&,TFALL(NPNTS) ! IN Throughfall (kg/m2/s). APA1F405.168
&,CAN_WCNT(NPNTS) ! IN Canopy water content (kg/m2). APA1F405.169
&,CAN_CPY(NPNTS) ! IN Canopy capacity (kg/m2). APA1F405.170
&,INFIL(NPNTS) ! IN Maximum infiltration rate (kg/m2/s). APA1F405.171
APA1F405.172
! Array arguments with intent(OUT): APA1F405.173
REAL APA1F405.174
& RUNOFF(NPNTS) ! OUT Surface runoff (kg/m2/s). APA1F405.175
APA1F405.176
! Local scalars: APA1F405.177
INTEGER APA1F405.178
& I ! WORK Loop counter. APA1F405.179
APA1F405.180
REAL APA1F405.181
& AEXP,AEXP1,AEXP2 ! WORK Exponential terms. APA1F405.182
&,CAN_RATIO ! WORK Fractional saturation of the APA1F405.183
C ! canopy. APA1F405.184
&,CM ! WORK (CAN_CPY - CAN_WCNT)/TIMESTEP APA1F405.185
C ! (kg/m2/s). APA1F405.186
*IF DEF,SCMA,AND,-DEF,T3E APA1F405.187
REAL*8 BIG_TMP ! SCM double real. APA1F405.188
*ENDIF APA1F405.189
APA1F405.190
! Local parameters: APA1F405.191
*CALL MOSES_OPT 
APA1F405.192
APA1F405.193
C----------------------------------------------------------------------- FRUNOF1A.34
C Uniform canopy water APA1F405.194
C----------------------------------------------------------------------- FRUNOF1A.36
IF (TF_MODEL.EQ.1) THEN APA1F405.195
DO I=1,NPNTS APA1F405.196
IF (R(I).GT.0.0) THEN APA1F405.197
IF (INFIL(I)*TIMESTEP.LE.CAN_WCNT(I).AND. APA1F405.198
& CAN_CPY(I).GT.0.0) THEN APA1F405.199
C----------------------------------------------------------------------- FRUNOF1A.41
C Equation (P252.14A) APA1F405.200
C----------------------------------------------------------------------- FRUNOF1A.43
AEXP=AREA*CAN_CPY(I)/R(I) APA1F405.201
IF (CAN_WCNT(I).GT.0.0) THEN APA1F405.202
AEXP1=EXP(-AEXP*INFIL(I)/CAN_WCNT(I)) APA1F405.203
ELSE APA1F405.204
AEXP1=0.0 APA1F405.205
ENDIF APA1F405.206
AEXP2=EXP(-AEXP/TIMESTEP) APA1F405.207
CAN_RATIO=CAN_WCNT(I)/CAN_CPY(I) APA1F405.208
*IF DEF,SCMA,AND,-DEF,T3E APA1F405.209
IF (AEXP1 .LT. 1E-30) AEXP1=0.0 APA1F405.210
IF (AEXP2 .LT. 1E-30) AEXP2=0.0 APA1F405.211
BIG_TMP= DBLE(R(I)) * (DBLE(CAN_RATIO * AEXP1) + APA1F405.212
& (1.0 - CAN_RATIO)*AEXP2) APA1F405.213
IF (BIG_TMP .LT. 1E-35) BIG_TMP=0.0 APA1F405.214
RUNOFF(I)=BIG_TMP APA1F405.215
*ELSE APA1F405.216
RUNOFF(I)=R(I)*(CAN_RATIO*AEXP1+(1.0-CAN_RATIO)*AEXP2) APA1F405.217
*ENDIF APA1F405.218
ELSE APA1F405.219
C----------------------------------------------------------------------- FRUNOF1A.60
C Equation (P254.14B) APA1F405.220
C----------------------------------------------------------------------- FRUNOF1A.62
CM=(CAN_CPY(I)-CAN_WCNT(I))/TIMESTEP APA1F405.221
*IF DEF,SCMA,AND,-DEF,T3E APA1F405.222
IF (( AREA*(INFIL(I)+CM)/R(I)) .GT. 30) THEN APA1F405.223
AEXP=0 APA1F405.224
ELSE APA1F405.225
AEXP = EXP( -AREA*(INFIL(I)+CM)/R(I)) APA1F405.226
ENDIF APA1F405.227
BIG_TMP=DBLE(R(I))*AEXP APA1F405.228
IF (BIG_TMP .LT. 1E-35) THEN APA1F405.229
RUNOFF(I)=0. APA1F405.230
ELSE APA1F405.231
RUNOFF(I)=BIG_TMP APA1F405.232
ENDIF APA1F405.233
*ELSE APA1F405.234
AEXP=EXP(-AREA*(INFIL(I)+CM)/R(I)) APA1F405.235
RUNOFF(I)=R(I)*AEXP APA1F405.236
*ENDIF APA1F405.237
ENDIF APA1F405.238
ELSE APA1F405.239
RUNOFF(I)=R(I) APA1F405.240
ENDIF APA1F405.241
ENDDO APA1F405.242
APA1F405.243
C----------------------------------------------------------------------- FRUNOF1A.67
C Bimodal canopy water APA1F405.244
C----------------------------------------------------------------------- FRUNOF1A.69
ELSEIF (TF_MODEL.EQ.2.OR.TF_MODEL.EQ.3) THEN APA1F405.245
DO I=1,NPNTS APA1F405.246
IF (R(I).GT.0.0) THEN APA1F405.247
*IF DEF,SCMA,AND,-DEF,T3E APA1F405.248
IF (( AREA*(INFIL(I))/R(I)) .GT. 30) THEN APA1F405.249
RUNOFF(I)= 0 APA1F405.250
ELSE APA1F405.251
RUNOFF(I)=TFALL(I)*EXP(-AREA*INFIL(I)/R(I)) APA1F405.252
ENDIF APA1F405.253
*ELSE APA1F405.254
RUNOFF(I)=TFALL(I)*EXP(-AREA*INFIL(I)/R(I)) APA1F405.255
*ENDIF APA1F405.256
ELSE APA1F405.257
RUNOFF(I)=R(I) APA1F405.258
ENDIF APA1F405.259
ENDDO APA1F405.260
ENDIF APA1F405.261
RETURN FRUNOF1A.153
END FRUNOF1A.154
*ENDIF FRUNOF1A.155