resdlem 0.0.4

A package to calulate equilibrium function for dlem

resdlem

Description

The resdlem python package provides a simple means of incorporating the Daily Lake Evaporation Model (DLEM) equilibrium function into python code.

It simply performs the calculation given the inputs. There is no unit support or other fluf. See below for inputs of the function and the units.

Code Example

from resdlem import equilibrium

devap = equilibrium.dlemEvap(
    lat=40,
    depth=20,
    elev=1000,
    solrad=270,
    ta=10,
    vpd=1,
    pres=89651.51985730644,
    ut=5,
    tw0=10,
    fch=1000,
    mth=5,
    tds=15_000,
    alb=0.1)

evap_hs = devap.evap_hs
tw = devap.tw

Function inputs

variable	Description	Units
lat	Latitude	degrees
depth	Average depth of reservoir (capacity/area)	meter
elev	Elevation of water surface	meter
solrad	Incoming surface shortwave solar radiation	W m-2 per day
ta	Daily average temperature	Celcius
vpd	Vapor pressure deficit	kPa
pres	Atmospheric Pressure	Pa
ut	Wind speed at 2m	m s-1
tw0	Water temp from previous timestep (tw)	Celcius
fch	Fetch length	m
mth	Month of interest	NA
tds	Total dissolved solids	ppm
alb	Water Body Albedo	NA

Function outputs

variable	Description	Units
evap_hs	Evaporation with Heat Storage	mm/day
evap_hs_adj	Evaporation with Heat Storage adjusted for total dissolved solids	mm/day
evap_nhs	Evaporation no Heat Storage (Penman Evaporation)	mm/day
te	Equilibrium Temperature	Celcius
tw	Water column temperature at end of timestep	Celcius
rn	Net solar radiation	W m-2 per day
ierr	Calculation code error (See Error Table)

Error Table (ierr)

value	Description
0	Timestep is good
2	Depth is less than or equal to 0
3	Air temperature is less than wet bulb temperature
4	Downloading solar radiation is less than 0
5	Wind speed is less than 0.01m/s
6	Vapor Pressure Deficit is less than or euqal to 0
7	Vapor pressure deficit is greater than saturated vapor pressure

Citation

Zhao, B., Huntington, J., Pearson, C., Zhao, G., Ott, T., Zhu, J., Weinberg, A., Holman, K. D., Zhang, S.,Anderson, R., Strickler, M., Cotter, J., Fernando, N., Nowak, K., & Gao, H. (2024).Developing a general Daily Lake Evaporation Model and demonstrating its application inthe state of Texas. Water Resources Research, 60(3), e2023WR036181. Available at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023WR036181