Trend assessment of annual instantaneous maximum flows in Turkey

Figures & data

Figure 1. Demonstration of increasing, decreasing and trendless areas according to Sen’s trend method on a Cartesian coordinate system.

Table 1. Turkish river basins with selected gauging stations and their basic statistical characteristics.

Basin no.	Basin name	Stations	Area of basin (× 10^3 km^2)	Basin average height (m)	Average precipitation (mm/year)	Total streamflow (km^3/year)
1	Meriç	101,103,106	14.560	56.63	604.0	1.33
2	Marmara	211,212,213,214,215	24.100	42.25	728.7	8.33
3	Susurluk	302,311,314,316,317,321,324,328	22.399	201.56	711.6	5.43
4	Aegean	410	10.003	63.75	624.2	2.09
5	Gediz	509,514,515,518,522,523,524,525,527	18.000	220.06	603.0	1.95
6	Little Menderes	601	6.907	4.00	727.4	1.19
7	Big Menderes	701,704,706,712,713,730,732,733,734	24.976	413.83	664.3	3.03
8	West Mediterranean	808,809,811,812,815,818	20.953	383.47	875.8	8.93
9	Central Mediterranean	902,912,917,918	19.577	248.85	100.4	11.06
10	Burdur Lake	-	6.374	910.0	446.3	0.50
11	Afyon	1102	7.605	1016.67	451.8	0.49
12	Sakarya	1203,1218,1219,1221,1222,1224,1226,1233,1237,1250	58.160	508.62	524.7	6.40
13	West Black Sea	1302,1307,1314,1319,1327,1330,1331,1332,1334,1335,1338,1339,1340	29.598	325.67	811.0	9.93
14	Yeşilırmak	1401,1402,1412,1413,1414,1418,1422,1424,1427	36.114	695.63	496.5	5.80
15	Kızılırmak	1501,1517,1532,1535,1538,1539,1541	78.180	748.48	446.1	6.48
16	Middle Anatolia	1611,1612,1621,1622	53.850	1139.37	416.8	4.52
17	East Mediterranean	1712,1714,1717,1719,1720,1721	22.048	269.05	745.0	11.07
18	Seyhan	1801,1805,1818,1820,1822	20.450	749.68	624.0	8.01
19	Hatay	1905,1906,1907,1908	7.796	159.17	815.6	1.17
20	Ceyhan	2004,2006,2008,2009,2020,2022,	21.982	684.81	731.6	7.18
21	Euphrates	2102,2115,2122,2124,2131,2133,2135,2145,2149,2151,2154,2156,2158,2164,2166,2177	127.304	1009.87	540.1	31.61
22	East Black Sea	2202,2213,2215,2218,2232,2233,2238,2245,2247	24.077	443.24	1198.2	14.90
23	Çoruh	2304,2305,2316,2320,2321,2323,2325,2328,2329,2330,	19.872	757.39	629.4	6.30
24	Aras	2409,2415,2418	27.548	1652.65	432.4	4.63
25	Van Lake	2505	19.405	1829.29	474.3	2.39
26	Tigris	2610,2612,2624	57.614	844.79	807.2	21.33
		Total	Total	Average	Average	Average
		153	779.452	591.49	658.86	186.05

Figure 2. Study area and spatial distribution of streamflow gauge stations used in the present study.

Figure 3. Map of median magnitudes of the AIMF series used in this study.

Table 2. The computed lag-1 autocorrelations, which are statistically significant, and the MK and SR test results (before and after the TFPW method).

Station no.	Before TFPW^a			Before TFPW^b		After TFPW^c			After TFPW^d		mMK		1.96/√N*
	lag-1	Z	Trend	Z	Trend	lag-1	Z	Trend	Z	Trend	Z	Trend
106	0.30	1.382	–	1.235	–	–0.01	1.572	–	1.279	–	0.934	–	0.28
311	0.34	–3.512	↓	–3.698	↓	–0.05	–3.022	↓	–3.119	↓	–3.512	↓	0.27
316	0.55	–5.437	↓	–5.195	↓	0.13	–4.885	↓	–4.626	↓	–6.037	↓	0.27
317	0.35	–2.383	↓	–2.622	↓	0.09	–2.912	↓	–3.073	↓	–2.383	↓	0.28
321	0.33	–3.230	↓	–3.248	↓	0.09	–2.897	↓	–2.928	↓	–3.027	↓	0.28
324	0.40	–3.662	↓	–3.648	↓	0.17	–3.724	↓	–3.635	↓	–3.662	↓	0.28
518	0.59	–5.789	↓	–5.478	↓	0.26	–5.370	↓	–5.016	↓	–5.788	↓	0.27
601	0.28	–3.093	↓	–2.959	↓	0.05	–2.959	↓	–2.983	↓	–3.093	↓	0.27
706	0.64	–4.387	↓	–4.099	↓	0.25	–5.580	↓	–5.163	↓	–4.546	↓	0.26
712	0.36	–5.014	↓	–5.075	↓	–0.05	–5.058	↓	–4.893	↓	–5.013	↓	0.26
713	0.42	–5.627	↓	–5.165	↓	0.15	–5.453	↓	–4.838	↓	–5.626	↓	0.27
818	0.43	2.728	↑	2.513	↑	0.12	2.935	↑	2.890	↑	3.377	↑	0.43
1340	0.40	–2.927	↓	–2.970	↓	0.07	–2.462	↓	–2.484	↓	–2.926	↓	0.35
1401	0.44	–4.241	↓	–4.270	↓	0.16	–4.233	↓	–4.268	↓	–4.241	↓	0.27
1402	0.38	–4.545	↓	–4.453	↓	0.13	–4.553	↓	–4.388	↓	–5.656	↓	0.27
1412	0.49	–4.600	↓	–4.440	↓	0.20	–4.758	↓	–4.629	↓	–2.554	↓	0.27
1501	0.27	–3.805	↓	–3.711	↓	0.05	–3.984	↓	–4.022	↓	–3.805	↓	0.26
1538	0.49	–2.937	↓	–2.928	↓	0.06	–2.855	↓	–3.001	↓	–2.332	↓	0.30
1719	−0.33	–0.967	–	–1.105	–	0.02	–0.338	–	–0.336	–	–0.967	–	0.30
1801	0.30	–0.259	–	–0.338	–	0.03	–0.301	–	–0.396	–	–0.259	–	0.27
1822	0.38	–3.915	↓	–3.917	↓	0.07	–3.934	↓	–4.019	↓	–3.914	↓	0.29
2004	0.32	–3.884	↓	–3.771	↓	0.08	–3.611	↓	–3.643	↓	–3.884	↓	0.29
2006	0.32	–1.201	–	–1.231	–	–0.01	–1.194	–	–1.269	–	–1.201	–	0.26
2020	0.57	–4.726	↓	–4.676	↓	0.17	–5.207	↓	–4.825	↓	–3.911	↓	0.28

*Critical value at the α = 0.05 significance level.

^aMK test results at 95% significance level (before applying TFPW).

^bSR test results at 95% significance level (before applying TFPW).

^cMK test results at 95% significance level (after applying TFPW).

^dSR test results at 95% significance level (after applying TFPW).

Figure 4. Autocorrelation plots (before and after pre-whitening) of the AIMF series for selected stations.

Figure 5. Spatial representation of the MK and SR trend test results with a significance level of 0.05 for the AIMF series.

Figure 6. Spatial pattern of the trend magnitudes computed using Sen’s slope method.

Table 3. Performance evaluation and comparison of the MK and Sen’s trend methods for all the stations in this study.

Station no.	STM (m^3/s)			MK	Station no.	STM (m^3/s)			MK	Station no.	STM (m^3/s)			MK	Station no.	STM (m^3/s)			MK
	L	M	H			L	M	H			L	M	H			L	M	H
101	0–60 ▼	60–140 ▼	140–320 ▼	▼	515	0–160 –	160–470 ▼	470–1260 ▼	–	811	0–100 ▼	100–250 ▼	250–500 ▼	▼	1302	0–200 ▼	200–350 ▼	350–550 ▼	▼
103	0–700 –	700–1300 –	1300–1800 –	–	518	0–240 ▼	240–500 ▼	500–820 ▼	▼	812	0–600 ▼	600–1000 ▼	1000–1500 ▼	–	1307	0–100 –	100–180 ▲	180–230 ▲	–
106	0–150 ▲	150–400 ▼	400–660 ▼	–	522	0–160 ▼	160–420 ▼	420–900 ▼	▼	815	0–380 –	380–750 ▼	750–1350 ▼	–	1314	0–250 ▼	250–480 –	480–700 ▼	–
211	0–40 –	40–80 ▲	80–280 ▲	▲	523	0–200 –	200–500 ▼	500–1300 ▼	–	818	0–120 ▲	120–200 ▲	200–300 ▲	▲	1319	0–60 –	60–170 –	170–380 –	–
212	0–380 –	380–630 ▼	630–1800 ▼	–	524	0–20 ▲	20–40 ▲	40–100 –	▲	902	0–800 –	800–1450 –	1450–2600 ▼	–	1327	0–100 ▼	100–180 ▼	180–230 ▼	▼
213	0–40 –	40–80 –	80–120 –	–	525	0–20 –	20–40 ▼	40–160 ▼	▼	912	0–520 –	520–780 ▼	780–920 –	–	1330	0–10 –	10–20 –	20–140 –	–
214	0–110 –	110–310 –	310–440 ▼	–	527	0–200 –	200–500 –	500–1600 ▼	–	917	0–400 –	400–900 ▼	900–1250 ▼	–	1331	0–370 –	370–900 ▲	900–1450 ▲	▲
215	0–100 ▲	100–160 ▲	160–610 ▲	▲	601	0–100 ▼	100–280 ▼	280–700 ▼	▼	918	0–730 –	730–1250 ▼	1250–1650 ▼	–	1332	0–70 ▼	70–90 ▼	90–110 ▼	▼
302	0–500 –	500–1200 ▼	1200–2500 ▼	▼	701	0–230 ▼	230–390 ▼	390–560 ▼	▼	1102	0–5 ▼	5–15 ▼	15–50 ▼	▼	1334	0–60 –	60–90 –	90–270 –	–
311	0–50 ▼	50–150 ▼	150–200 ▼	▼	704	0–80 –	80–180 –	180–480 –	–	1203	0–30 ▼	30–90 ▼	90–220 ▼	▼	1335	0–900 ▼	900–1800 ▼	1800–2820 ▼	–
314	0–580 –	580–1390 ▼	1390–1700 –	–	706	0–180 ▼	180–300 ▼	300–410 ▼	▼	1218	0–300 ▼	300–450 –	450–610 ▼	–	1338	0–70 ▲	70–200 ▲	200–260 ▲	–
316	0–620 ▼	620–1240 ▼	1240–2400 ▼	▼	712	0–100 ▼	100–220 ▼	220–540 ▼	▼	1219	0–120 ▲	120–180 –	180–270 ▼	–	1339	0–40 –	40–90 –	90–170 –	–
317	0–470 ▼	470–770 ▼	770–970 ▼	▼	713	0–30 ▼	30–50 ▼	50–110 ▼	▼	1221	0–400 ▼	400–700 ▼	700–1010 ▼	▼	1340	0–240 –	240–450 ▼	450–900 ▲	▼
321	0–120 ▼	120–180 ▼	180–360 ▼	▼	730	0–10 –	10–70 ▲	70–190 ▼	–	1222	0–160 –	160–270 –	270–400 ▲	–	1401	0–400 ▼	400–680 ▼	680–1030 ▼	▼
324	0–240 ▼	240–380 ▼	380–550 ▼	▼	732	0–340 –	340–950 ▼	950–110 –	–	1224	0–20 ▼	20–40 ▼	40–90 ▼	▼	1402	0–600 ▼	600–950 ▼	950–1260 ▼	▼
328	0–70 –	70–180 ▼	180–280 ▼	▼	733	0–60 –	60–180 ▲	180–280 ▲	–	1226	0–60 ▼	60–160 ▼	160–210 ▼	▼	1412	0–40 ▼	40–120 ▼	120–180 ▼	▼
410	0–30 –	30–90 –	90–110 ▼	–	734	0–340 –	340–550 ▲	550–600 ▲	–	1233	0–180 ▼	180–420 ▼	420–680 ▼	–	1413	0–320 ▼	320–500 –	500–740 ▼	–
509	0–125 ▼	125–250 ▼	250–440 ▼	–	808	0–40 ▼	40–80 ▼	80–180 ▼	–	1237	0–50 –	50–150 ▼	150–260 ▼	–	1414	0–100 ▼	100–180 ▼	180–260 ▼	▼
514	0–100 ▼	100–500 ▼	500–1000 ▼	▼	809	0–60 –	60–150 ▲	150–260 ▲	–	1250	0–20 –	20–120 ▼	120–150 –	–	1418	0–180 –	180–250 –	250–500 –	–
1422	0–70 –	70–120 –	120–230 ▼	–	1801	0–200 –	200–400 –	400–710 ▼	–	2133	0–520 –	520–800 –	800–1340 –	–	2304	0–80 –	80–160 –	160–300 –	–
1424	0–30 –	30–60 –	60–90 –	–	1805	0–500 –	500–1000 ▼	1000–2000 ▼	–	2135	0–30 –	30–60 –	60–130 ▼	–	2305	0–360 –	360–570 ▲	570–700 –	–
1427	0–200 ▼	200–500 ▼	500–630 ▼	▼	1818	0–1000 –	1000–1950 –	1950–3280 ▼	–	2145	0–100 ▼	100–200 ▼	200–370 ▼	▼	2316	0–240 –	240–400 ▲	400–560 –	–
1501	0–360 ▼	360–680 ▼	680–1100 ▼	▼	1820	0–140 –	140–220 –	220–530 ▼	–	2149	0–320 ▲	320–480 –	480–1140 ▼	–	2320	0–160 –	160–260 –	260–330 –	–
1517	0–50 ▼	50–100 ▼	100–370 ▼	▼	1822	0–70 ▼	70–100 ▼	100–190 ▼	▼	2151	0–430 –	430–700 –	700–1020 –	–	2321	0–80 –	80–100 –	100–130 ▲	–
1532	0–420 –	420–800 –	800–1410 –	–	1905	0–100 –	100–180 –	180–270 –	–	2154	0–160 –	160–240 –	240–370 ▲	–	2323	0–230 –	230–360 –	360–510 –	–
1535	0–300 ▼	300–500 ▼	500–600 ▼	–	1906	0–170 ▼	170–380 ▼	380–1000 ▼	▼	2156	0–600 –	600–970 ▼	970–1160 –	–	2325	0–70 ▼	70–150 ▼	150–200 ▼	–
1538	0–120 ▼	120–210 ▼	210–560 ▼	▼	1907	0–110 ▼	110–180 ▼	180–200 ▼	▼	2158	0–210 –	210–38 ▼	380–760 ▼	▼	2328	0–40 ▼	40–70 ▼	70–90 ▼	▼
1539	0–160 ▼	160–300 ▼	300–370 ▼	▼	1908	0–370 ▼	370–590 –	590–1010 ▲	–	2164	0–500 –	500–800 ▼	800–1100 ▼	–	2329	0–160 –	160–300 ▲	300–400 ▲	–
1541	0–100 ▼	100–190 ▼	190–230 ▼	▼	2004	0–860 –	860–1340 ▼	1340–2500 ▼	▼	2166	0–600 –	600–1250 ▼	1250–1500 ▼	–	2330	0–20 ▼	20–30 ▼	30–60 ▼	▼
1611	0–30 –	30–60 –	60–180 –	–	2006	0–50 –	50–80 –	80–150 ▼	–	2177	0–240 ▼	240–350 ▼	350–530 ▼	▼	2409	0–120 –	120–270 –	270–610 ▲	–
1612	0–15 –	15–30 ▼	30–45 ▼	–	2008	0–140 –	140–250 –	250–600 –	–	2202	0–90 –	90–150 –	150–270 –	–	2415	0–160 –	160–280 –	280–400 ▲	–
1621	0–40 ▲	40–60 ▲	60–70 ▲	▲	2009	0–60 –	60–140 –	140–500 ▼	▼	2213	0–120 –	120–220 ▼	220–400 ▼	–	2418	0–140 –	140–320 –	320–770 –	–
1622	0–5 –	5–15 ▼	15–45 ▼	▼	2020	0–570 ▼	570–1650 ▼	1650–2000 ▼	▼	2215	0–80 –	80–110 –	110–190 –	–	2505	0–70 –	70–130 –	130–220 ▼	–
1712	0–220 –	220–380 –	380–520 ▼	–	2022	0–40 –	40–130 ▼	130–200 ▼	–	2218	0–140 –	140–280 ▼	280–510 ▼	▼	2610	0–200 –	200–370 –	370–450 –	–
1714	0–720 ▼	720–1250 ▼	1250–2000 –	▼	2102	0–1800 –	1800–3000 ▼	3000–3560 ▼	–	2232	0–150 –	150–250 –	250–560 ▼	–	2612	0–1330 ▼	1330–2000 ▼	2000–2670 ▼	▼
1717	0–20 –	20–60 –	60–440 –	▼	2115	0–380 –	380–700 ▼	700–2320 ▼	▼	2233	0–40 –	40–60 –	60–80 –	–	2624	0–240 –	240–440 –	440–600 –	–
1719	0–630 –	630–1100 –	1100–2500 ▲	–	2122	0–490 –	490–870 –	870–1130 –	–	2238	0–150 –	150–230 –	230–510 ▼	–
1720	0–280 –	280–550 –	550–700 ▼	–	2124	0–40 ▼	40–70 ▼	70–110 ▼	▼	2245	0–220 –	220–550 –	540–1000 –	–
1721	0–250 –	250–400 –	400–640 ▼	–	2131	0–15 –	15–50 ▼	50–160 ▼	▼	2247	0–350 ▼	350–1000 ▼	1000–1300 ▼	▼

▲,▼ and – symbols represent increasing trend, decreasing trend and no trend, respectively.

STM indicates Sen’s trend method.

L, M and H represent low, medium and high flows, respectively.

Figure 7. Results of Sen’s trend method for selected stations.

Figure 8. Spatial distribution of the increasing trends in medium or high clusters.