gwflow: sd_ch(chan_id)%chd is the channel depth, but is used as the daily water depth in gwflow_channel_exch and gwflow_floodplain

[crazyzlj]

The channel depth sd_ch(chan_id)%chd is used in gwflow_channel_exch and gwflow_floodplain.

!characteristics of channel
chan_depth = sd_ch(chan_id)%chd !depth (m) of water in channel

However, the chan_depth should be set to the daily updated water depth in the channel.