Water stable isotopes in the Yarlungzangbo headwater region and its vicinity of the southwestern Tibetan Plateau

Figures & data

Fig. 1 (a) Geographical location of the Yarlungzangbo headwater region; (b) sample location map of various waters from the Yarlungzangbo headwater region and its vicinity, showing the upper Yarlungzangbo flows from the Jiemayangzong Glacier in the western Himalaya to the site near Saga; (c) sample location map of waters in the Yarlungzangbo source area. Some sample numbers are also shown.

Fig. 2 (a) δ¹⁸O and δD results of all waters in relation to the GMWL (δD=δ¹⁸O+10) (samples are divided into four categories based upon their geographical locations and the lake/pond sample numbers are shown); (b) δ¹⁸O and δD results of various types of water in the Yarlungzangbo headwaters. The local water line (LWL) is developed using isotopic data of snow, ice, river and stream samples.

Table 1. Sample localities and measured isotopic data

Sample	Sampling date	Lat. (°N)	Long. (°E)	Sampling elevation (m a.s.l.)	δ^18O (‰)	δD (‰)	d-excess^c (‰)	Note
River/stream waters
1^a	2012/07/16	30.2548	82.2135	5064	−14.64	−104.9	12.2	Main flow (outflow of the JMYZ Glacier lake)
2^a	2012/07/16	30.4324	82.3018	4943	−13.27	−97.7	8.5	Main flow (Rebujie Co lake)
3^a	2012/07/16	30.3507	82.7380	4719	−13.09	−96.7	8.0	Main flow (above the confluence with Mayouzangbo)
4^a	2012/07/16	30.3507	82.8705	4670	−14.18	−105.8	7.6	Main flow (below the confluence with Mayouzangbo)
5^a	2012/07/18	29.7785	83.9067	4584	−14.26	−106.6	7.5	Main flow (outflow of a large flow-through lake)
6^a	2012/07/18	29.3194	85.2592	4477	−15.79	−118.8	7.5	Main flow (near Saga)
7	2012/07/03	30.2618	82.2268	5026	−14.96	−109	10.7	Stream (near the JMYZ Glacier)
8	2012/07/03	30.2805	82.2574	5027	−13.10	−96.4	8.4	Stream (near the JMYZ Glacier)
9	2012/07/03	30.3525	82.6216	4773	−12.92	−96.7	6.7	Stream
10	2012/07/09	30.4005	82.1390	5037	−15.60	−110	14.8	River (Angsequ)
11	2012/07/09	30.3737	82.0618	5270	−14.07	−95.7	16.9	Stream
12	2012/07/02	30.2583	81.1001	3905	−12.53	−83.4	16.8	Stream (near Pulan)
13	2012/07/02	30.2580	81.0646	4294	−11.09	−71.0	17.7	Stream (near Pulan)
14	2012/07/02	30.2930	81.1653	3916	−12.50	−84.3	15.7	Stream (near Pulan)
15	2012/07/02	30.2318	81.1044	4616	−11.96	−79.7	16.0	Stream (near Pulan)
16	2012/07/02	30.2095	81.0659	4773	−12.42	−82.4	17.0	Stream (near Pulan)
17	2012/07/02	30.9650	81.2113	4637	−15.60	−113.3	11.5	Stream
18	2012/07/02	30.9570	81.2752	4626	−14.75	−105.9	12.1	Stream
19	2012/07/02	30.8901	81.3730	4627	−14.71	−105.6	12.1	Stream
20	2012/07/05	30.8612	81.4268	4631	−14.03	−103.4	8.9	Stream
21	2012/07/02	30.8387	81.4525	4625	−14.52	−106.3	9.9	Stream
22	2012/07/05	30.9664	81.5000	4870	−14.32	−103.9	10.6	Stream
23	2012/07/02	30.7767	81.6137	4623	−16.00	−121.6	6.4	Stream
24	2012/07/02	30.5376	82.5751	4923	−16.49	−120.4	11.5	River (Mayouzangbo)
25	2012/07/04	30.5208	82.6042	4874	−16.85	−125.9	8.9	River (Mayouzangbo)
26	2012/07/02	30.4964	82.6153	4836	−16.25	−118.8	11.2	River (Mayouzangbo)
27	2012/07/04	30.3736	82.7803	4730	−16.15	−117.0	12.2	River (Mayouzangbo)
28	2012/07/02	30.2764	82.9491	4653	−16.65	−124.8	8.4	Stream
29	2012/07/03	30.2324	82.9941	4640	−16.98	−124.4	11.4	Stream
30	2012/07/03	30.2157	83.0158	4630	−16.59	−121.7	11.1	Stream
31	2012/07/03	30.1321	83.3071	4608	−17.15	−130.4	6.8	Stream
32	2012/07/03	30.1280	83.3284	4594	−17.55	−133.2	7.2	Stream
33	2012/07/03	29.7117	84.0697	4569	−18.41	−139.9	7.4	River (Caiqu, near Zhongba)
34	2012/07/17	29.5931	84.4477	4576	−17.98	−132.8	11.0	Stream
35	2012/07/17	29.5568	84.9198	4651	−17.64	−134.1	7.0	River (Jiadazangbo)
36	2012/07/17	29.4274	85.2342	4715	−18.09	−135.3	9.4	Stream
37^b	2012/07/18	29.4724	85.9521	4887	−18.09	−140.1	4.6	River (Qiangxiongzangbo)
38^b	2012/07/18	29.4825	86.0266	4814	−18.46	−145.0	2.7	Stream
39^b	2012/07/18	29.4797	86.1909	4790	−18.67	−148.1	1.3	Stream
40^b	2012/07/18	29.4920	86.4911	4655	−17.68	−138.5	2.9	River (Duoxiongzangbo)
41^b	2012/07/20	29.3206	87.0144	4454	−18.60	−146.3	2.5	Stream
42^b	2012/07/20	29.0879	88.0387	4266	−18.57	−146.0	2.6	Stream
43^b	2012/07/20	29.1498	88.0873	4150	−18.29	−144.5	1.8	Stream
44^b	2012/07/20	29.2125	88.3695	3877	−18.15	−141.6	3.6	Stream
45^b	2012/07/20	29.2754	88.8962	3839	−17.02	−131.0	5.1	River (Nyangqu, near Xigaze)
Surface snow
46	2012/07/16	30.2472	82.2042	5116	−13.21	−92.5	13.2	In ablation zone of the JMYZ Glacier
47	2012/07/16	30.2356	82.1822	5334	−11.01	−76.2	11.9	In ablation zone of the JMYZ Glacier
48	2012/07/02	30.2383	81.0394	4842	−9.22	−54.8	18.9	Near Pulan
Glacier ice
49	2012/07/16	30.2353	82.1850	5307	−15.76	−112	14.1	In ablation zone of the JMYZ Glacier
50	2012/07/16	30.2389	82.1922	5239	−16.92	−120.2	15.1	In ablation zone of the JMYZ Glacier
51	2012/07/16	30.2442	82.2003	5143	−14.79	−105.4	12.9	In ablation zone of the JMYZ Glacier
Pond water
52	2012/07/16	30.2572	82.2174	5096	−7.00	−59.0	−3.0	Deep (~3 m), with no outlet/inlet, near the JMYZ Glacier lake
53	2012/07/16	30.3136	82.2816	5057	−10.64	−79.9	5.2	Large, shallow and connected with the main channel through a narrow opening
54	2012/07/09	30.4353	82.1813	5018	−6.22	−67.7	−18.0	Shallow, with no outlet/inlet, far from any river channel or glacier
Lake water
55	2012/07/01	30.7144	81.3707	4598	−2.79	−46.3	−24.0	The lake of the Manasarovar
56	2012/07/01	30.6650	81.3215	4680	−2.20	−37.7	−20.1	The lake of the Lhanag Co

^aMain flow of the upper Yarlungzangbo. ^bOut of the range of Fig. 1b and were sampled from Xigaze westward to Saga. ^cd-excess=δD – 8δ¹⁸O.

Fig. 3 δ¹⁸O and δD of surface snow/glacier ice (in the ablation zone of the Jiemayangzong Glacier), glacier lake and stream water samples in the Jiemayangzong Glacier area.

Fig. 4 Main flow (upper Yarlungzangbo) and tributary influx δ¹⁸O vs. distance downstream from the JMYZ Glacier (0 km) to Saga (~370 km).

Fig. 5 Plot of river/stream δ¹⁸O, d-excess and sampling altitude vs. longitude. These samples do not include main flows in the Yarlungzangbo and waters collected from the western Himalaya. Blue lines represent individual variation trends for each section.

Fig. 6 (a) Schematic representation of the buildup of the predicted LEL relative to LMWL (local meteoric water line) for a given region. δp_s is the isotopic composition in precipitation in average thaw season. δ_A is the average isotopic composition in evaporative-flux-weighted atmospheric moisture and is assumed to be in approximate isotopic equilibrium with δp_s. δss is the isotopic composition in a terminal (closed-drainage) basin fed by annual mean precipitation with an isotopic value of δp in a steady state (evaporation=inflow, E=I). δ* represents the theoretical limiting isotopic composition attainable for water bodies under average evaporative conditions in summer (Appendix A). (b) Isotopic compositions in various waters from the Yarlungzangbo source region (above the confluence with the Mayouzangbo) and the Manasarovar/Lhanag Co region in relation to the LWL and the predicted LEL.