Merge pull request natcap#1550 from dcdenu4/bugfix/1541-swy-qfi-bad-sum

Fix a quickflow summation bug in SWY

HISTORY.rst

@@ -99,6 +99,10 @@ Unreleased Changes
     * Fixed an issue with the precip directory units. Units for these input
       rasters are now correctly stated as mm/month.
       https://github.com/natcap/invest/issues/1571
+    * Fixed an issue where the monthly quickflow values were being summed over
+      a block area and not summed pixelwise. This caused the quickflow
+      output ``QF.tif`` to have malformed values.
+      https://github.com/natcap/invest/issues/1541
 * Wind Energy
     * Fixed a bug where some number inputs were not being properly cast to
       ``float`` or ``int`` types. If the inputs happened to be passed as

src/natcap/invest/seasonal_water_yield/seasonal_water_yield.py

@@ -901,7 +901,7 @@ def execute(args):
             ],
             dependent_task_list=[
                 align_task, flow_dir_task, stream_threshold_task,
-                fill_pit_task, qf_task] + quick_flow_task_list,
+                fill_pit_task] + quick_flow_task_list,
             task_name='calculate local recharge')
 
     # calculate Qb as the sum of local_recharge_avail over the AOI, Eq [9]
@@ -973,7 +973,7 @@ def execute(args):
 
 
 # raster_map equation: sum the monthly qfis
-def qfi_sum_op(*qf_values): return numpy.sum(qf_values)
+def qfi_sum_op(*qf_values): return numpy.sum(qf_values, axis=0)
 
 
 def _calculate_l_avail(l_path, gamma, target_l_avail_path):