示例#1
0
    def __init__(self, modern_dem_name, outlet_id, chi_mask_dem_name=None, from_file=None):
        """Initialize MetricCalculator with names of postglacial and modern
        DEMs."""


        if from_file is None:

            # Read and remember the modern DEM (whether data or model)
            (self.grid, self.z) = self.read_topography(modern_dem_name)
            #print self.grid.x_of_node
    
            self.grid.set_watershed_boundary_condition_outlet_id(outlet_id,
                                                                 self.z, nodata_value=-9999)
    
            # Instantiate and run a FlowRouter and lake filler, so we get
            # drainage area for cumulative-area statistic, and also fields for chi.
            fr = FlowRouter(self.grid)
            dfr = DepressionFinderAndRouter(self.grid)
            fr.route_flow()
            dfr.map_depressions()
    
            # Remember modern drainage area grid
            self.area = self.grid.at_node['drainage_area']
    
            # Instantiate a ChiFinder for chi-index
            self.chi_finder = ChiFinder(self.grid, min_drainage_area=10000.,
                                        reference_concavity=0.5)
            
            core_nodes = np.zeros(self.area.shape, dtype=bool)
            core_nodes[self.grid.core_nodes] = True
            # Read and remember the MASK, if provided
            if chi_mask_dem_name is None:
                 self.mask = (self.area>1e5)
                 self.till_mask = np.zeros(self.mask.shape, dtype=bool) 
                 self.till_mask[self.grid.core_nodes] = 1
            else:
                (self.mask_grid, zmask) = self.read_topography(chi_mask_dem_name)
                mask = (zmask>0)*1
                self.mask = (self.area>1e5)*(mask==1)
                
                mask_bool = (zmask>0)
                self.till_mask = np.zeros(self.mask.shape, dtype=bool) 
                self.till_mask[mask_bool*core_nodes] = 1
            # 
            
            # Create dictionary to contain metrics
            self.metric = {}
        
        else:
            with open(from_file, 'r') as f:
                metrics = load(f)
                self.modern_dem_name = metrics.pop('Topo file')

                self.metric = metrics
    
            fn_split = from_file.split('.')
            fn_split[-1] = 'chi'
            fn_split.append('txt')
            chi_filename = '.'.join(fn_split)
            self.density_chi = np.loadtxt(chi_filename)
def test_track_source():
    """Unit tests for track_source().
    """
    grid = RasterModelGrid((5, 5), spacing=(1., 1.))
    grid.at_node['topographic__elevation'] = np.array([5., 5., 5., 5., 5.,
                                                       5., 4., 5., 1., 5.,
                                                       0., 3., 5., 3., 0.,
                                                       5., 4., 5., 2., 5.,
                                                       5., 5., 5., 5., 5.])
    grid.status_at_node[10] = 0
    grid.status_at_node[14] = 0
    fr = FlowRouter(grid)
    fr.route_flow()
    r = grid.at_node['flow__receiver_node']
    assert_equal(r[6], 10)
    assert_equal(r[7], 8)
    assert_equal(r[18], 14)
    hsd_ids = np.empty(grid.number_of_nodes, dtype=int)
    hsd_ids[:] = 1
    hsd_ids[2:5] = 0
    hsd_ids[7:10] = 0
    (hsd_upstr, flow_accum) = track_source(grid, hsd_ids)
    assert_equal(hsd_upstr[8], [1, 0, 0])
    assert_equal(hsd_upstr[14], [1, 1, 1, 1, 0, 0, 1])
    assert_equal(flow_accum[14], 7)
def test_find_unique_upstream_hsd_ids_and_fractions():
    """Unit tests find_unique_upstream_hsd_ids_and_fractions().
    """
    grid = RasterModelGrid((5, 5), spacing=(1., 1.))
    grid.at_node['topographic__elevation'] = np.array([
        5., 5., 5., 5., 5., 5., 4., 5., 1., 5., 0., 3., 5., 3., 0., 5., 4., 5.,
        2., 5., 5., 5., 5., 5., 5.
    ])
    grid.status_at_node[10] = 0
    grid.status_at_node[14] = 0
    fr = FlowRouter(grid)
    fr.route_flow()
    hsd_ids = np.empty(grid.number_of_nodes, dtype=int)
    hsd_ids[:] = 1
    hsd_ids[2:5] = 0
    hsd_ids[7:10] = 0
    (hsd_upstr, flow_accum) = track_source(grid, hsd_ids)
    (uniq_ids, coeff) = find_unique_upstream_hsd_ids_and_fractions(hsd_upstr)
    np.testing.assert_almost_equal(np.sort(np.array(coeff[8])),
                                   np.array([0.33333333, 0.66666667]))
def test_find_unique_upstream_hsd_ids_and_fractions():
    """Unit tests find_unique_upstream_hsd_ids_and_fractions().
    """
    grid = RasterModelGrid((5, 5), spacing=(1., 1.))
    grid.at_node['topographic__elevation'] = np.array([5., 5., 5., 5., 5.,
                                                       5., 4., 5., 1., 5.,
                                                       0., 3., 5., 3., 0.,
                                                       5., 4., 5., 2., 5.,
                                                       5., 5., 5., 5., 5.])
    grid.status_at_node[10] = 0
    grid.status_at_node[14] = 0
    fr = FlowRouter(grid)
    fr.route_flow()
    hsd_ids = np.empty(grid.number_of_nodes, dtype=int)
    hsd_ids[:] = 1
    hsd_ids[2:5] = 0
    hsd_ids[7:10] = 0
    (hsd_upstr, flow_accum) = track_source(grid, hsd_ids)
    (uniq_ids, coeff) = find_unique_upstream_hsd_ids_and_fractions(hsd_upstr)
    np.testing.assert_almost_equal(
        np.sort(np.array(coeff[8])), np.array([0.33333333, 0.66666667]))
def test_track_source():
    """Unit tests for track_source().
    """
    grid = RasterModelGrid((5, 5), spacing=(1., 1.))
    grid.at_node['topographic__elevation'] = np.array([
        5., 5., 5., 5., 5., 5., 4., 5., 1., 5., 0., 3., 5., 3., 0., 5., 4., 5.,
        2., 5., 5., 5., 5., 5., 5.
    ])
    grid.status_at_node[10] = 0
    grid.status_at_node[14] = 0
    fr = FlowRouter(grid)
    fr.route_flow()
    r = grid.at_node['flow__receiver_node']
    assert r[6] == 10
    assert r[7] == 8
    assert r[18] == 14
    hsd_ids = np.empty(grid.number_of_nodes, dtype=int)
    hsd_ids[:] = 1
    hsd_ids[2:5] = 0
    hsd_ids[7:10] = 0
    (hsd_upstr, flow_accum) = track_source(grid, hsd_ids)
    assert hsd_upstr[8] == [1, 0, 0]
    assert hsd_upstr[14] == [1, 1, 1, 1, 0, 0, 1]
    assert flow_accum[14] == 7
side_length = 4 #m, block side length
tau_c_br = 10 #Pa, for now
a1 = 6.5
a2 = 2.5
d = 0.1 #z0
tol = 0.01 #m water thickness error allowable

elapsed_time = 0.
keep_running = True
counter = 0 # simple incremented counter to let us see the model advance
while keep_running:
    if elapsed_time + dt > runtime:
        dt = runtime - elapsed_time
        keep_running = False
    #route flow to determine water volume flux in each cell
    _ = fr.route_flow() # route_flow isn't time sensitive, so it doesn't take dt as input
    
    #lake filling stuff here
    try:
        _ = lf.map_depressions()
        #_ = lf.route_flow() #route flow given that lakes may exist
    except AssertionError:
        print 'Be careful, depression filler took too many iterations'
    print counter
    print np.amin(mg['node']['topographic__elevation'])
    print '-----'
    #test = mg['node']['upstream_ID_order']
    #sys.exit('f**k you')
    #turn volume flux into specific discharge by dividing by channel width
    water_vol_flux = mg['node']['water__volume_flux'] #/ 365 / 24 / 3600 #drainage area times rain rate
    water_specific_q = water_vol_flux / channel_width
示例#7
0
def test_composite_pits():
    """
    A test to ensure the component correctly handles cases where there are
    multiple pits, inset into each other.
    """
    mg = RasterModelGrid(10, 10, 1.)
    z = mg.add_field("node", "topographic__elevation", mg.node_x.copy())
    # a sloping plane
    # np.random.seed(seed=0)
    # z += np.random.rand(100)/10000.
    # punch one big hole
    z.reshape((10, 10))[3:8, 3:8] = 0.
    # dig a couple of inset holes
    z[57] = -1.
    z[44] = -2.
    z[54] = -10.

    # make an outlet
    z[71] = 0.9

    fr = FlowRouter(mg)
    lf = DepressionFinderAndRouter(mg)
    fr.route_flow()
    lf.map_depressions()

    flow_sinks_target = np.zeros(100, dtype=bool)
    flow_sinks_target[mg.boundary_nodes] = True
    # no internal sinks now:
    assert_array_equal(mg.at_node["flow__sink_flag"], flow_sinks_target)

    # test conservation of mass:
    assert mg.at_node["drainage_area"].reshape((10, 10))[1:-1, 1].sum() == approx(
        8. ** 2
    )
    # ^all the core nodes

    # test the actual flow field:
    #    nA = np.array([  0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.,
    #                     8.,   8.,   7.,   6.,   5.,   4.,   3.,   2.,   1.,   0.,
    #                     1.,   1.,   1.,   1.,   1.,   1.,   1.,   1.,   1.,   0.,
    #                     1.,   1.,   1.,   4.,   2.,   2.,   8.,   4.,   1.,   0.,
    #                     1.,   1.,   1.,   8.,   3.,  15.,   3.,   2.,   1.,   0.,
    #                     1.,   1.,   1.,  13.,  25.,   6.,   3.,   2.,   1.,   0.,
    #                     1.,   1.,   1.,  45.,   3.,   3.,   5.,   2.,   1.,   0.,
    #                    50.,  50.,  49.,   3.,   2.,   2.,   2.,   4.,   1.,   0.,
    #                     1.,   1.,   1.,   1.,   1.,   1.,   1.,   1.,   1.,   0.,
    #                     0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.,   0.])
    nA = np.array(
        [
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            8.,
            8.,
            7.,
            6.,
            5.,
            4.,
            3.,
            2.,
            1.,
            0.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            0.,
            1.,
            1.,
            1.,
            4.,
            2.,
            2.,
            6.,
            4.,
            1.,
            0.,
            1.,
            1.,
            1.,
            6.,
            3.,
            12.,
            3.,
            2.,
            1.,
            0.,
            1.,
            1.,
            1.,
            8.,
            20.,
            4.,
            3.,
            2.,
            1.,
            0.,
            1.,
            1.,
            1.,
            35.,
            5.,
            4.,
            3.,
            2.,
            1.,
            0.,
            50.,
            50.,
            49.,
            13.,
            10.,
            8.,
            6.,
            4.,
            1.,
            0.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            1.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
        ]
    )
    assert_array_equal(mg.at_node["drainage_area"], nA)

    # the lake code map:
    lc = np.array(
        [
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            57,
            57,
            57,
            57,
            57,
            XX,
            XX,
            XX,
            XX,
            XX,
            57,
            57,
            57,
            57,
            57,
            XX,
            XX,
            XX,
            XX,
            XX,
            57,
            57,
            57,
            57,
            57,
            XX,
            XX,
            XX,
            XX,
            XX,
            57,
            57,
            57,
            57,
            57,
            XX,
            XX,
            XX,
            XX,
            XX,
            57,
            57,
            57,
            57,
            57,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
        ]
    )

    # test the remaining properties:
    assert lf.lake_outlets.size == 1
    assert lf.lake_outlets[0] == 72
    outlets_in_map = np.unique(lf.depression_outlet_map)
    assert outlets_in_map.size == 2
    assert outlets_in_map[1] == 72
    assert lf.number_of_lakes == 1
    assert lf.lake_codes[0] == 57
    assert_array_equal(lf.lake_map, lc)
    assert lf.lake_areas[0] == approx(25.)
    assert lf.lake_volumes[0] == approx(63.)
示例#8
0
def test_three_pits():
    """
    A test to ensure the component correctly handles cases where there are
    multiple pits.
    """
    mg = RasterModelGrid(10, 10, 1.)
    z = mg.add_field("node", "topographic__elevation", mg.node_x.copy())
    # a sloping plane
    # np.random.seed(seed=0)
    # z += np.random.rand(100)/10000.
    # punch some holes
    z[33] = 1.
    z[43] = 1.
    z[37] = 4.
    z[74:76] = 1.
    fr = FlowRouter(mg)
    lf = DepressionFinderAndRouter(mg)
    fr.route_flow()
    lf.map_depressions()

    flow_sinks_target = np.zeros(100, dtype=bool)
    flow_sinks_target[mg.boundary_nodes] = True
    # no internal sinks now:
    assert_array_equal(mg.at_node["flow__sink_flag"], flow_sinks_target)

    # test conservation of mass:
    assert mg.at_node["drainage_area"].reshape((10, 10))[1:-1, 1].sum() == approx(
        8. ** 2
    )
    # ^all the core nodes

    # test the actual flow field:
    nA = np.array(
        [
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            8.,
            8.,
            7.,
            6.,
            5.,
            4.,
            3.,
            2.,
            1.,
            0.,
            2.,
            2.,
            1.,
            1.,
            2.,
            1.,
            1.,
            1.,
            1.,
            0.,
            26.,
            26.,
            25.,
            15.,
            11.,
            10.,
            9.,
            8.,
            1.,
            0.,
            2.,
            2.,
            1.,
            9.,
            2.,
            1.,
            1.,
            1.,
            1.,
            0.,
            2.,
            2.,
            1.,
            1.,
            5.,
            4.,
            3.,
            2.,
            1.,
            0.,
            2.,
            2.,
            1.,
            1.,
            1.,
            1.,
            3.,
            2.,
            1.,
            0.,
            20.,
            20.,
            19.,
            18.,
            17.,
            12.,
            3.,
            2.,
            1.,
            0.,
            2.,
            2.,
            1.,
            1.,
            1.,
            1.,
            3.,
            2.,
            1.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
        ]
    )
    assert_array_equal(mg.at_node["drainage_area"], nA)

    # test a couple more properties:
    lc = np.empty(100, dtype=int)
    lc.fill(XX)
    lc[33] = 33
    lc[43] = 33
    lc[37] = 37
    lc[74:76] = 74
    assert_array_equal(lf.lake_map, lc)
    assert_array_equal(lf.lake_codes, [33, 37, 74])
    assert lf.number_of_lakes == 3
    assert lf.lake_areas == approx([2., 1., 2.])
    assert lf.lake_volumes == approx([2., 2., 4.])
示例#9
0
def test_degenerate_drainage():
    """
    This "hourglass" configuration should be one of the hardest to correctly
    re-route.
    """
    mg = RasterModelGrid(9, 5)
    z_init = mg.node_x.copy() * 0.0001 + 1.
    lake_pits = np.array([7, 11, 12, 13, 17, 27, 31, 32, 33, 37])
    z_init[lake_pits] = -1.
    z_init[22] = 0.  # the common spill pt for both lakes
    z_init[21] = 0.1  # an adverse bump in the spillway
    z_init[20] = -0.2  # the spillway
    z = mg.add_field("node", "topographic__elevation", z_init)

    fr = FlowRouter(mg)
    lf = DepressionFinderAndRouter(mg)
    fr.route_flow()
    lf.map_depressions()

    #    correct_A = np.array([ 0.,   0.,   0.,   0.,   0.,
    #                           0.,   1.,   3.,   1.,   0.,
    #                           0.,   5.,   1.,   2.,   0.,
    #                           0.,   1.,  10.,   1.,   0.,
    #                          21.,  21.,   1.,   1.,   0.,
    #                           0.,   1.,   9.,   1.,   0.,
    #                           0.,   3.,   1.,   2.,   0.,
    #                           0.,   1.,   1.,   1.,   0.,
    #                           0.,   0.,   0.,   0.,   0.])

    correct_A = np.array(
        [
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
            1.,
            3.,
            1.,
            0.,
            0.,
            2.,
            4.,
            2.,
            0.,
            0.,
            1.,
            10.,
            1.,
            0.,
            21.,
            21.,
            1.,
            1.,
            0.,
            0.,
            1.,
            9.,
            1.,
            0.,
            0.,
            2.,
            2.,
            2.,
            0.,
            0.,
            1.,
            1.,
            1.,
            0.,
            0.,
            0.,
            0.,
            0.,
            0.,
        ]
    )

    thelake = np.concatenate((lake_pits, [22])).sort()

    assert mg.at_node["drainage_area"] == approx(correct_A)
示例#10
0
def test_edge_draining():
    """
    This tests when the lake attempts to drain from an edge, where an issue
    is suspected.
    """
    # Create a 7x7 test grid with a well defined hole in it, AT THE EDGE.
    mg = RasterModelGrid((7, 7), (1., 1.))

    z = mg.node_x.copy()
    guard_sides = np.concatenate((np.arange(7, 14), np.arange(35, 42)))
    edges = np.concatenate((np.arange(7), np.arange(42, 49)))
    hole_here = np.array(([15, 16, 22, 23, 29, 30]))
    z[guard_sides] = z[13]
    z[edges] = -2.  # force flow outwards from the tops of the guards
    z[hole_here] = -1.

    A_new = np.array(
        [
            [
                [
                    0.,
                    1.,
                    1.,
                    1.,
                    1.,
                    1.,
                    0.,
                    0.,
                    1.,
                    1.,
                    1.,
                    1.,
                    1.,
                    0.,
                    15.,
                    5.,
                    4.,
                    3.,
                    2.,
                    1.,
                    0.,
                    0.,
                    10.,
                    4.,
                    3.,
                    2.,
                    1.,
                    0.,
                    0.,
                    1.,
                    4.,
                    3.,
                    2.,
                    1.,
                    0.,
                    0.,
                    1.,
                    1.,
                    1.,
                    1.,
                    1.,
                    0.,
                    0.,
                    1.,
                    1.,
                    1.,
                    1.,
                    1.,
                    0.,
                ]
            ]
        ]
    ).flatten()

    depr_outlet_target = np.array(
        [
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            14,
            14,
            XX,
            XX,
            XX,
            XX,
            XX,
            14,
            14,
            XX,
            XX,
            XX,
            XX,
            XX,
            14,
            14,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
            XX,
        ]
    ).flatten()

    mg.add_field("node", "topographic__elevation", z, units="-")

    fr = FlowRouter(mg)
    lf = DepressionFinderAndRouter(mg)

    fr.route_flow()
    lf.map_depressions()
    assert mg.at_node["drainage_area"] == approx(A_new)
    assert lf.depression_outlet_map == approx(depr_outlet_target)
示例#11
0
extend_t[0:lat.shape[0] - 1, lon.shape[0] * 2:lon.shape[0] *
         3] = ice_topo_f[0:lat.shape[0] - 1, :]  # Top right
extend_t[lat.shape[0] - 1:lat.shape[0] * 2 - 2,
         0:lon.shape[0] * 3] = np.fliplr(
             np.flipud(extend_t[0:lat.shape[0] - 1,
                                0:lon.shape[0] * 3]))  # pad bottom

# Create raster grid for flow calculation and add data
fg = RasterModelGrid((extend_t.shape[0], extend_t.shape[1]), spacing=(1, 1))
_ = fg.add_field('node', 'topographic__elevation', extend_t)

fg.set_closed_boundaries_at_grid_edges(False, False, False, False)

# Calculate flow fields
fr = FlowRouter(fg)
fg = fr.route_flow()

# Preview the flow field with this plotting func.
# drainage_plot(fg, title='Grid 2 using FlowDirectorD8')

# Fill in Lakes/depressions
fg.at_node['flow__sink_flag'][
    fg.core_nodes].sum()  # how many depressions do we have?
hf = SinkFiller(fg, apply_slope=True)
hf.run_one_step()
fr.run_one_step()
# drainage_plot(fg, title='Grid 2 using FlowDirectorD8')
# Output is a single vector
flow_rec = fg.at_node['flow__receiver_node']

# Convert to a 'tocell' field
示例#12
0
side_length = 4  #m, block side length
tau_c_br = 10  #Pa, for now
a1 = 6.5
a2 = 2.5
d = 0.1  #z0
tol = 0.01  #m water thickness error allowable

elapsed_time = 0.
keep_running = True
counter = 0  # simple incremented counter to let us see the model advance
while keep_running:
    if elapsed_time + dt > runtime:
        dt = runtime - elapsed_time
        keep_running = False
    #route flow to determine water volume flux in each cell
    _ = fr.route_flow(
    )  # route_flow isn't time sensitive, so it doesn't take dt as input

    #lake filling stuff here
    try:
        _ = lf.map_depressions()
        #_ = lf.route_flow() #route flow given that lakes may exist
    except AssertionError:
        print 'Be careful, depression filler took too many iterations'
    print counter
    print np.amin(mg['node']['topographic__elevation'])
    print '-----'
    #test = mg['node']['upstream_ID_order']
    #sys.exit('f**k you')
    #turn volume flux into specific discharge by dividing by channel width
    water_vol_flux = mg['node'][
        'water__volume_flux']  #/ 365 / 24 / 3600 #drainage area times rain rate
# Display initialization message
print('Running ...') 

#instantiate the components:
pr = PrecipitationDistribution(input_file)
fr = Flow(mg)
sp = Fsc(mg, input_file)
hd = Diff(mg, input_file)

####################RUN
track_uplift = 0 #track cumulative uplift to know top of hard layer
last_trunc = runtime
for (interval_duration, rainfall_rate) in pr.yield_storm_interstorm_duration_intensity():
    if rainfall_rate != 0.:
        # note diffusion also only happens when it's raining...
        _ = fr.route_flow()
        _ = sp.erode(mg, interval_duration, K_if_used='K_values')
        _ = hd.diffuse(interval_duration)
    track_uplift += uplift_rate * interval_duration #top of beginning surface
    mg.at_node['topographic__elevation'][mg.core_nodes] += uplift_rate * interval_duration
    this_trunc = pr.elapsed_time // t_plot
    if this_trunc != last_trunc: # time to plot a new profile!
        print ('Time %d' % (t_plot * this_trunc))
        last_trunc = this_trunc
    else:
        pass
    
    #check where hard rocks and soft rocks are, change k to reflect this
    if hard_layer_on_or_off == 1: #if using layers
        hard_layer = np.where(mg.at_node['topographic__elevation'] >= track_uplift - hard_layer_thickness)
        soft_layer = np.where(mg.at_node['topographic__elevation'] < track_uplift - hard_layer_thickness)
示例#14
0
def extend_perturbed_runs(total_iters_to_reach=0):
    """Load all perturbed runs in current folder, and extend them.

    Function should be called from within an experiment folder
    (extend all perturbations for all starting uplift rates), an
    'uplift_rate_XXXX' folder (extend all perturbations for this rate) or an
    'accel_XXX' folder (extend this accel only).

    Does NOT create a new expt or run ID, just extends the old ones. Adds a
    text file annotating what has happened.
    """
    # look for the params to use. Also tells us where we are in the hierarchy
    level = 0  # 0: top, 1: uplift, 2: accel:
    cwd = os.getcwd()
    while True:
        try:
            paramdict = np.load('expt_ID_paramdict.npy').item()
        except IOError:
            os.chdir('..')
            level += 1
        else:
            break
    # now back to where we started in the dir str:
    os.chdir(cwd)
    if level == 2:  # in accel_ folder
        # get the accel that this is:
        accel_factors = [
            get_float_of_folder_name(),
        ]
        # get the U of the host folder:
        uplift_rates = [
            get_float_of_folder_name(directory=(cwd + '/..')),
        ]
        wd_stub = os.path.abspath(os.getcwd() + '/../..')
    elif level == 1:  # in uplift_ folder
        accel_fnames = [
            filename for filename in os.listdir('.')
            if filename.startswith('accel_')
        ]
        accel_factors = [
            get_float_of_folder_name(directory=(cwd + '/' + filename))
            for filename in accel_fnames
        ]
        uplift_rates = [
            get_float_of_folder_name(),
        ]
        wd_stub = os.path.abspath(os.getcwd() + '/..')
    elif level == 0:  # in top folder
        uplift_fnames = [
            filename for filename in os.listdir('.')
            if filename.startswith('uplift_rate_')
        ]
        uplift_rates = [
            get_float_of_folder_name(directory=(cwd + '/' + filename))
            for filename in uplift_fnames
        ]
        accel_factors = paramdict['accel_factors']
        wd_stub = os.path.abspath(os.getcwd())

    for uplift_rate in uplift_rates:
        for accel_factor in accel_factors:
            wd = (wd_stub + '/uplift_rate_' + str(uplift_rate) + '/accel_' +
                  str(accel_factor))
            # get the saved filenames that already exist in this folder:
            runnames = [
                filename for filename in os.listdir(wd)
                if filename.startswith('topographic__elevation')
            ]
            seddepthnames = [
                filename for filename in os.listdir(wd)
                if filename.startswith('channel_sediment__depth')
            ]
            # as elsewhere, the final entry is the last run, so --
            # establish the loop number of that run:
            run_ID = runnames[-1][-14:-4]  # is a str
            _format = 0
            while True:
                char = runnames[-1][-16 - _format]
                try:
                    num = int(char)
                except ValueError:  # was a str
                    break
                else:
                    _format += 1
            finaliter = int(runnames[-1][(-15 - _format):-15])
            finalsediter = int(seddepthnames[-1][(-15 - _format):-15])
            assert finaliter == finalsediter  # ...just in case

            # test we need to actually do more runs:
            if total_iters_to_reach < finaliter + paramdict['out_interval']:
                continue

            # check we aren't going to have a "zero problem"; correct if we do
            max_zeros = len(str(total_iters_to_reach))
            if max_zeros + 1 > _format:  # less won't be possible from continue
                extra_zeros = max_zeros + 1 - _format
                for allfile in os.listdir(wd):
                    if allfile[-14:-4] == run_ID:
                        os.rename(
                            wd + '/' + allfile,
                            (wd + '/' + allfile[:(-15 - _format)] +
                             '0' * extra_zeros + allfile[(-15 - _format):]))
                runnames = [
                    filename for filename in os.listdir(wd)
                    if filename.startswith('topographic__elevation')
                ]
                seddepthnames = [
                    filename for filename in os.listdir(wd)
                    if filename.startswith('channel_sediment__depth')
                ]
            if max_zeros + 1 < _format:
                max_zeros = _format - 1  # in case of any bonus 0s from old run

            # build the structures:
            mg = RasterModelGrid(paramdict['shape'], paramdict['dx'])
            for edge in (mg.nodes_at_left_edge, mg.nodes_at_top_edge,
                         mg.nodes_at_right_edge):
                mg.status_at_node[edge] = CLOSED_BOUNDARY

            z = mg.add_zeros('node', 'topographic__elevation')
            seddepth = mg.add_zeros('node', 'channel_sediment__depth')
            fr = FlowRouter(mg)
            eroder = SedDepEroder(mg, **paramdict)
            ld = LinearDiffuser(mg, **paramdict)

            # load the last available elev data:
            z[:] = np.loadtxt(wd + '/' + runnames[-1])
            seddepth[:] = np.loadtxt(wd + '/' + seddepthnames[-1])

            # save a note
            try:
                appendfile = open(wd + '/appended_run_readme.txt', 'a')
            except IOError:
                appendfile = open(wd + '/appended_run_readme.txt', 'w')
            appendfile.write('This run was appended at timestamp ' +
                             str(int(time.time())) + '.\n')
            appendfile.write('New loops were added from iteration ' +
                             str(finaliter) + ' and terminated at iteration ' +
                             str(total_iters_to_reach) + '.\n\n')
            appendfile.close()

            # get runnin'
            print('Extending uplift ' + str(uplift_rate) + ' accel ' +
                  str(accel_factor) + ' from iter number ' + str(finaliter))
            dt = paramdict['dt']
            for i in xrange(finaliter + 1, total_iters_to_reach):
                fr.route_flow()
                eroder.run_one_step(dt)
                ld.run_one_step(dt)
                z[mg.core_nodes] += accel_factor * uplift_rate * dt
                print(i)
                if i % out_interval == 0:
                    zeros_to_add = max_zeros - len(str(i)) + 1
                    # note an OoM buffer! Just to be safe
                    if zeros_to_add < 0:
                        # ...just in case, though should never happen
                        print('Problem allocating zeros on savefiles')
                    ilabel = '0' * zeros_to_add + str(i)
                    identifier = ilabel + '_' + str(run_ID)
                    for field in out_fields:
                        np.savetxt(
                            wd + '/' + field + '_' + identifier + '.txt',
                            mg.at_node[field])
z = mg.add_zeros('node', 'topographic__elevation')
z += np.random.rand(mg.number_of_nodes)

mg.status_at_node[mg.nodes_at_left_edge] = CLOSED_BOUNDARY
mg.status_at_node[mg.nodes_at_right_edge] = CLOSED_BOUNDARY

fr = FlowRouter(mg)
sp = FastscapeEroder(mg, K_sp=1.e-5)
sf = SteepnessFinder(mg, min_drainage_area=1.e5)

dt = 20000.

for i in xrange(100):
    print(i)
    fr.route_flow()
    sp.run_one_timestep(dt)
    mg.at_node['topographic__elevation'][mg.core_nodes] += 1.

sf.calculate_steepnesses()
edges = mg.ones('node', dtype=bool)
edges.reshape(mg.shape)[2:-2, 2:-2] = False
steepness_mask = np.logical_or(sf.hillslope_mask, edges)
steepnesses = np.ma.array(mg.at_node['channel__steepness_index'],
                          mask=steepness_mask)
imshow_grid_at_node(mg, 'topographic__elevation')
imshow_grid_at_node(mg, steepnesses, color_for_closed=None,
                    cmap='winter')
plt.show()

dt=10000.